Lung cancer is the malignant transformation and expansion of lung tissue, and is responsible for 1.3 million deaths worldwide annually.[1] It is the most common cause of cancer-related death in men, and the second most common in women.[2][3]
Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens, especially tobacco smoke.[4] While some people who have never smoked do still get lung cancer, this appears to be due to a combination of genetic factors[5] and exposure to secondhand smoke.[6][7] Radon gas[8] and air pollution may also contribute to the development of lung cancer.[9][10][11]
Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Treatments include surgery, chemotherapy, and radiotherapy.[12]
Signs and symptoms
Symptoms that suggest lung cancer include:[12]
dyspnea (shortness of breath)
hemoptysis (coughing up blood)
chronic coughing or change in regular coughing pattern
wheezing
chest pain or pain in the abdomen
cachexia (weight loss), fatigue and loss of appetite
dysphonia (hoarse voice)
clubbing of the fingernails (uncommon)
difficulty swallowing
If the cancer grows in the airway, it may obstruct airflow, causing breathing difficulties. This can lead to accumulation of secretions behind the blockage, predisposing the patient to pneumonia.
Many lung cancers have a rich blood supply. The surface of the cancer may be fragile, leading to bleeding from the cancer into the airway. This blood may subsequently be coughed up.
Depending on the type of tumor, so-called paraneoplastic phenomena may initially attract attention to the disease. In lung cancer, this may be Lambert-Eaton myasthenic syndrome (muscle weakness due to auto-antibodies), hypercalcemia and SIADH. Tumors in the top (apex) of the lung, known as Pancoast tumors, may invade the local part of the sympathetic nervous system, leading to changed sweating patterns and eye muscle problems (a combination known as Horner's syndrome), as well as muscle weakness in the hands due to invasion of the brachial plexus.
In many patients, the cancer has already spread beyond the original site by the time they have symptoms and seek medical attention. Common sites of metastasis include the bone, such as the spine (causing back pain and occasionally spinal cord compression), the liver and the brain.
About 10% of people with lung cancer do not have symptoms of it at the time of diagnosis; these cancers are usually found on routine chest x-rays.[12]
Unfortunately, many of the symptoms of lung cancer (bone pain, fever, weight loss ) are nonspecific and in the elderly may be attributed to comorbid illness. [13]
Causes
Exposure to carcinogens in tobacco smoke causes cumulative changes to the tissue lining the bronchi of the lungs (the bronchial mucous membrane) and more tissue gets damaged until a tumour develops.
There are four major causes of lung cancer (and cancer in general):
Carcinogens such as those in tobacco smoke
Radiation exposure
Genetic susceptibility
Viral infection
The role of smoking
The incidence of lung cancer is highly correlated with smoking. Source:NIH.Smoking, particularly of cigarettes, is by far the main contributor to lung cancer, which at least in theory makes it one of the easiest diseases to prevent. In the United States, smoking is estimated to account for 87% of lung cancer cases (90% in men and 79% in women), and in the UK for 90%. Cigarette smoke contains 19 known carcinogens[4] including radioisotopes from the radon decay sequence, nitrosamine, and benzopyrene. Additionally, nicotine appears to depress the immune response to malignant growths in exposed tissue. The length of time a person continues to smoke as well as the amount smoked increases the person's chances of developing lung cancer. If a person stops smoking, these chances steadily decrease as damage to the lungs is repaired and contaminant particles are gradually vacated. More recent work has shown that, across the developed world, almost 90% of lung cancer deaths are caused by smoking.[14] In addition, there is evidence that lung cancer in never-smokers has a better prognosis than in smokers,[15] and that patients who smoke at the time of diagnosis have shorter survival than those who have quit.[16] Passive smoking—the inhalation of smoke from another's smoking— is claimed to be a cause of lung cancer in non-smokers. Studies from the USA (1986,[17][18] 1992,[19] 1997,[20] 2001,[21] 2003[22]), Europe (1998[23]), the UK (1998[24][25]), and Australia (1997[26]) have consistently shown a significant increase in relative risk among those exposed to passive smoke.
In 1993, the United States Environmental Protection Agency (EPA) claimed that about 3,000 lung cancer-related deaths a year were caused by passive smoking. However, since this report was based on a study that was alleged to be heavily biased and was ruled by a federal judge to be "unscientific", the EPA report was declared null and void by a federal judge in 1998[27][28].
Percentage of lung cancer deaths attributable to smoking in the developed world 35-69 years 70 years+ All ages
Men 93.9% 90.3% 92.5%
Women 68.8% 68.9% 68.8%
Both 88.7% 84.3% 86.6%
The extensive attempts made by Philip Morris to delay the release of the 1997 IARC study, to affect the wording of its conclusions, to neutralise its negative results for their business, and to counteract its impact on public and policymakers' opinion have been documented by Ong & Glantz in The Lancet journal.[29] Their work was based on 32 million pages of documents made public as part of the settlement of the 1998 legal case of State of Minnesota and Blue Cross/Blue Shield of Minnesota vs Philip Morris Inc, et al. and available at Philip Morris' own website.[30]
Recent investigation of sidestream smoke suggests it is more dangerous than direct smoke inhalation.[31]
Asbestos
Asbestos can cause a variety of lung diseases. It increases the risk of developing lung cancer. There is a synergistic effect between tobacco smoking and asbestos in the formation of lung cancer.[32]
Asbestos can also cause cancer of the pleura, called mesothelioma (which is distinct from lung cancer).
Radon gas
Radon is a colorless and odourless gas generated by the breakdown of radioactive radium, which in turn is the decay product of uranium, found in the earth's crust. The radiation decay products ionize genetic material, causing mutations that sometimes turn cancerous. Radon exposure is the second major cause of lung cancer after smoking.[8]
Radon gas levels vary by locality and the composition of the underlying soil and rocks. For example, in areas such as Cornwall in the UK (which has granite as substrata), radon gas is a major problem, and buildings have to be force-ventilated with fans to lower radon gas concentrations. The United States Environmental Protection Agency (EPA) estimates that one in 15 homes in the USA has radon levels above the recommended guideline of 4 picoCuries per liter (pCi/L).[33] Iowa has the highest average radon concentration in the United States; studies performed there have demonstrated a 50% increased lung cancer risk with prolonged radon exposure above the EPA's action level of 4 pCi/L.[34][35]
Genetics and viruses
Oncogenes are genes that are believed make people more susceptible to cancer. Proto-oncogenes are believed to turn into oncogenes when exposed to particular carcinogens.[36] Viruses are known to cause lung cancer in animals[37][38] and recent evidence suggests similar potential in humans.[39][40]
Diagnosis
Chest x-ray showing lung cancer in the left lung.Performing a chest x-ray is the first step if a patient reports symptoms that may be suggestive of lung cancer. This may reveal an obvious mass, widening of the mediastinum (suggestive of spread to lymph nodes there), atelectasis (collapse), consolidation (infection) and pleural effusion. If there are no X-ray findings but the suspicion is high (e.g. a heavy smoker with blood-stained sputum), bronchoscopy and/or a CT scan may provide the necessary information. In any case, bronchoscopy or CT-guided biopsy is often necessary to identify the tumor type.[12]
CT scan showing lung cancer in the left lung.The differential diagnosis for patients who present with abnormalities on chest x-ray includes lung cancer, as well as other nonmalignant diseases. These include infectious causes such as tuberculosis or pneumonia, or inflammatory conditions such as sarcoidosis. These diseases can result in mediastinal lymphadenopathy or lung nodules, and sometimes mimic lung cancers.[13]
Types
There are two main types of lung cancer categorized by the size and appearance of the malignant cells seen by a histopathologist under a microscope: non-small cell (80%) and small-cell (roughly 20%) lung cancer.[12] This classification although based on simple pathomorphological criteria has very important implications for clinical management and prognosis of the disease.
Non-small cell lung cancer
The non-small cell lung cancers are grouped together because their prognosis and management are roughly identical. When it cannot be subtyped, it is frequently coded to 8046/3. The subtypes are:
Squamous cell carcinoma, accounting for 29% of lung cancers,[12] also starts in the larger bronchi but grows slower. This means that the size of these tumours varies on diagnosis.
Adenocarcinoma is the most common subtype of NSCLC, accounting for 32% of lung cancers.[12] It is a form which starts near the gas-exchanging surface of the lung. Most cases of adenocarcinoma are associated with smoking. However, among people who have never smoked ("never-smokers"), adenocarcinoma is the most common form of lung cancer.[41] A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have different responses to treatment.[42]
Large cell carcinoma is a fast-growing form, accounting for 9% of lung cancers,[12] that grows near the surface of the lung.
Small cell lung cancer
Small cell lung carcinoma (microscopic view of a core needle biopsy)SCLC (also called "oat cell carcinoma") is the less common form of lung cancer. It tends to start in the larger breathing tubes and grows rapidly becoming quite large. The oncogene most commonly involved is L-myc. The "oat" cell contains dense neurosecretory granules which give this an endocrine/paraneoplastic syndrome association. It is initially more sensitive to chemotherapy, but ultimately carries a worse prognosis and is often metastatic at presentation. This type of lung cancer is strongly associated with smoking.
Other types
Carcinoid
Adenoid cystic carcinoma
Cylindroma
Mucoepidermoid carcinoma
Metastatic cancers
The lung is a common place for metastasis from tumors in other parts of the body. These cancers, however, are identified by the site of origin, i.e., a breast cancer metastasis to the lung is still known as breast cancer. The adrenal glands, liver, brain, and bone are the most common sites of metastasis from primary lung cancer itself.
Lung cancer staging
Lung cancer staging is an assessment of the degree of spread of the cancer from its original source. It is an important contributor to the prognosis and potential treatment of lung cancer.
Non-small cell lung cancer is staged from IA ("one A", best prognosis) to IV ("four", worst prognosis).
See non-small cell lung cancer staging.[43]
Small cell lung cancer is classified as limited stage if it is confined to one half of the chest and within the scope of a single radiotherapy field. Otherwise it extensive stage.[44]
Treatment
Treatment for lung cancer depends on the cancer's specific cell type, how far it has spread, and the patient's performance status. Common treatments include surgery, chemotherapy, and radiation therapy. The 5-year overall survival rate is 14%.[12]
Surgery
If investigations confirm lung cancer, CT scan and often positron emission tomography (PET) are used to determine whether the disease is localised and amenable to surgery or whether it has spread to the point where it cannot be cured surgically.
Blood tests and spirometry (lung function testing) are also necessary to assess whether the patient is well enough to be operated on. If spirometry reveals a very poor respiratory reserve, as may occur in chronic smokers, surgery may be contraindicated.
Surgery itself has an overall operative death rate of 5%, depending on the patient's lung function and other risk factors.[45] Surgery is usually only an option in non-small cell lung cancer limited to one lung, up to stage IIIA. This is assessed with medical imaging (computed tomography, positron emission tomography). A sufficient pre-operative respiratory reserve must be present to allow adequate lung function after the tissue is removed.
Procedures include wedge excision (removal of part of a lobe), lobectomy (one lobe), bilobectomy (two lobes) or pneumonectomy (whole lung). In patients with adequate respiratory reserve, lobectomy is the preferred option, as this minimizes the chance of local recurrence. If the patient does not have enough functional lung for this, wedge excision may be performed.[46] Radioactive iodine brachytherapy at the margins of wedge excision may reduce recurrence to that of lobectomy.[47]
Chemotherapy
Small cell lung cancer is treated primarily with chemotherapy, as surgery has no demonstrable influence on survival. Primary chemotherapy is also given in metastatic non-small cell lung cancer.
The combination regimen depends on the tumour type:
NSCLC: cisplatin or carboplatin, in combination with gemcitabine, paclitaxel, docetaxel, etoposide or vinorelbine.[48]
SCLC: cisplatin and etoposide are most commonly used.[49] Combinations with carboplatin, gemcitabine, paclitaxel, vinorelbine, topotecan and irinotecan are also used.[50][51]
Adjuvant chemotherapy
Adjuvant chemotherapy refers to the use of chemotherapy after surgery to improve the outcome. During surgery, samples are taken from the lymph nodes. If these samples contain cancer, then the patient has stage II or III disease. In this situation, adjuvant chemotherapy may improve survival by up to 15%.[52][53]
Standard practice is to offer platinum-based chemotherapy (e.g. cisplatin and vinorelbine).[54]
Adjuvant chemotherapy for patients with stage IB cancer is controversial as clinical trials have not clearly demonstrated a survival benefit.[55][56]
Trials of preoperative chemotherapy (neoadjuvant chemotherapy) in resectable non-small cell lung cancer have been inconclusive.[57]
Targeted therapy
In recent years, various molecular targeted therapies have been developed for the treatment of advanced lung cancer. Gefitinib (Iressa) is one such drug, which targets the tyrosine kinase domain of the epidermal growth factor receptor (EGF-R) which is expressed in many cases of non-small cell lung cancer. However despite an exciting start it was not shown to increase survival, although females, Asians, non-smokers and those with the bronchioloalveolar carcinoma cell type appear to be deriving most benefit from gefitinib.[42]
Erlotinib (Tarceva), another tyrosine kinase inhibitor, has been shown to increase survival in lung cancer patients and has recently been approved by the FDA for second-line treatment of advanced non-small cell lung cancer. [Similar to gefitinib, it appeared to work best in females, Asians, non-smokers and those with the bronchioloalveolar carcinoma cell type.]
A number of targeted agents are at the early stages of clinical research, such as cyclo-oxygenase-2 (COX-2) inhibitors, the apoptosis promoter exisulind,[58] proteasome inhibitors, bexarotene (Targretin) and vaccines.[59]
Treatment of lung cancer is evolving.[60][61][62]
Radiotherapy
Radiotherapy is often given together with chemotherapy, and may be used with curative intent in patients who are not eligible for surgery. A radiation dose of 40 or more Gy in many fractions is commonly used with curative intent in non-small cell lung cancer; typically in North America, the dose prescribed is 60 or 66 Gy in 30 to 33 fractions given once daily, 5 days a week, for 6 to 6½ weeks. For small cell lung cancer cases that are potentially curable, in addition to chemotherapy, chest radiation is often recommended. For these small cell lung cancer cases, chest radiation doses of 40 Gy or more in many fractions are commonly given; typically in North America, the dose prescribed is 45 to 50 Gy and can be given in either once daily treatments for 5 weeks or twice daily treatments for 3 weeks.[63]
For both non-small cell lung cancer and small cell lung cancer patients, radiation of disease in the chest to smaller doses (typically 20 Gy in 5 fractions) may be used for symptom control.
Interventional radiology
Radiofrequency ablation is increasing in popularity for this condition as it is nontoxic and causes very little pain. It seems especially effective when combined with chemotherapy as it catches the cells deeper inside a tumor—the ones difficult to get with chemotherapy due to reduced blood supply to the center of the tumor. It is done by inserting a small heat probe into the tumor to kill the tumor cells.[64]
Prognosis
For non-small cell lung cancer, prognosis is poor. Following complete surgical resection of stage IA disease, five-year survival is 67%. With stage IB disease, five-year survival is 57%.[65] The 5-year survival rate of patients with stage IV NSCLC is about 1%.[66]
See non-small cell lung cancer staging.
For small cell lung carcinoma, prognosis is also poor. The overall five-year survival for patients with SCLC is about 5%.[12] Patients with extensive-stage SCLC have an average five-year survival rate of less than 1%. The median survival time for limited-stage disease is 20 months, with a five-year survival rate of 20%.[66]
See Manchester score.
Epidemiology
Lung cancer distribution in the United States.The population segment most likely to develop lung cancer is the over-fifties who also have a history of smoking. Lung cancer is the second most commonly occurring form of cancer in most western countries, and it is the leading cancer-related cause of death for men and women. In the US, 175,000 new cases are expected in 2006:[67] 90,700 in men and 80,000 in women. Although the rate of men dying from lung cancer is declining in western countries, it is actually increasing for women due to the increased takeup of smoking by this group. Among lifetime non-smokers, men who have never smoked have higher age-standardized lung cancer death rates than women. Of the 80,000 women who are diagnosed with lung cancer in 2006, approximately 70,000 are expected to die from it.[68]
Lung cancer was extremely rare prior to the advent of cigarette smoking. In 1878, malignant lung tumors made up only 1% of all cancers seen at autopsy; this had risen to 10-15% by the early 1900s.[69] Case reports in the medical literature numbered only 374 worldwide in 1912.[70] The British Doctors Study, published in the 1950s, first offered solid epidemiological evidence on the link between lung cancer and smoking.
Not all cases of lung cancer are due to smoking, but the role of passive smoking is increasingly being recognized as a risk factor for lung cancer, leading to policy interventions to decrease undesired exposure of non-smokers to others' tobacco smoke. Emissions from automobiles, factories and power plants also pose potential risks.[9][11][71]
Eastern Europe has the highest lung cancer mortality among men, while northern Europe and the USA have the highest mortality among women. Lung cancer incidence is less common in developing countries.[72]
Prevention
Primary prevention
Prevention is the most cost-effective means of fighting lung cancer on the national and global scales. While in most countries industrial and domestic carcinogens have been identified and banned, tobacco smoking is still widespread. Eliminating tobacco smoking is a primary goal in the prevention of lung cancer, and smoking cessation is an important preventative tool in this process.[73]
Policy interventions to decrease passive smoking (e.g. in restaurants and workplaces) have become more common in various Western countries, with California taking a lead in banning smoking in public establishments in 1998, Ireland playing a similar role in Europe in 2004, followed by Italy and Norway in 2005 and Scotland as well as several others in 2006 New Zealand has also recently banned smoking in public places. (See Smoking ban and list of smoking bans).
Only the Asian state of Bhutan has a complete smoking ban (since 2005). In many countries pressure groups are campaigning for similar bans. Arguments cited against such bans are criminalisation of smoking, increased risk of smuggling and the risk that such a ban cannot be enforced.
Screening
Main article: lung cancer screening
Screening refers to the use of medical tests to detect disease in asymptomatic people. Possible screening tests for lung cancer include chest x-ray or computed tomography (CT) of the chest.
So far, screening programs for lung cancer have not demonstrated any clear benefit. However randomized controlled studies are underway in this area to see if decreased long-term mortality can be directly observed from CT screening.[74]
Sunday, June 3, 2007
LUNG CANCER
Lung cancer is the malignant transformation and expansion of lung tissue, and is responsible for 1.3 million deaths worldwide annually.[1] It is the most common cause of cancer-related death in men, and the second most common in women.[2][3]
Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens, especially tobacco smoke.[4] While some people who have never smoked do still get lung cancer, this appears to be due to a combination of genetic factors[5] and exposure to secondhand smoke.[6][7] Radon gas[8] and air pollution may also contribute to the development of lung cancer.[9][10][11]
Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Treatments include surgery, chemotherapy, and radiotherapy.[12]
Signs and symptoms
Symptoms that suggest lung cancer include:[12]
dyspnea (shortness of breath)
hemoptysis (coughing up blood)
chronic coughing or change in regular coughing pattern
wheezing
chest pain or pain in the abdomen
cachexia (weight loss), fatigue and loss of appetite
dysphonia (hoarse voice)
clubbing of the fingernails (uncommon)
difficulty swallowing
If the cancer grows in the airway, it may obstruct airflow, causing breathing difficulties. This can lead to accumulation of secretions behind the blockage, predisposing the patient to pneumonia.
Many lung cancers have a rich blood supply. The surface of the cancer may be fragile, leading to bleeding from the cancer into the airway. This blood may subsequently be coughed up.
Depending on the type of tumor, so-called paraneoplastic phenomena may initially attract attention to the disease. In lung cancer, this may be Lambert-Eaton myasthenic syndrome (muscle weakness due to auto-antibodies), hypercalcemia and SIADH. Tumors in the top (apex) of the lung, known as Pancoast tumors, may invade the local part of the sympathetic nervous system, leading to changed sweating patterns and eye muscle problems (a combination known as Horner's syndrome), as well as muscle weakness in the hands due to invasion of the brachial plexus.
In many patients, the cancer has already spread beyond the original site by the time they have symptoms and seek medical attention. Common sites of metastasis include the bone, such as the spine (causing back pain and occasionally spinal cord compression), the liver and the brain.
About 10% of people with lung cancer do not have symptoms of it at the time of diagnosis; these cancers are usually found on routine chest x-rays.[12]
Unfortunately, many of the symptoms of lung cancer (bone pain, fever, weight loss ) are nonspecific and in the elderly may be attributed to comorbid illness. [13]
Causes
Exposure to carcinogens in tobacco smoke causes cumulative changes to the tissue lining the bronchi of the lungs (the bronchial mucous membrane) and more tissue gets damaged until a tumour develops.
There are four major causes of lung cancer (and cancer in general):
Carcinogens such as those in tobacco smoke
Radiation exposure
Genetic susceptibility
Viral infection
The role of smoking
The incidence of lung cancer is highly correlated with smoking. Source:NIH.Smoking, particularly of cigarettes, is by far the main contributor to lung cancer, which at least in theory makes it one of the easiest diseases to prevent. In the United States, smoking is estimated to account for 87% of lung cancer cases (90% in men and 79% in women), and in the UK for 90%. Cigarette smoke contains 19 known carcinogens[4] including radioisotopes from the radon decay sequence, nitrosamine, and benzopyrene. Additionally, nicotine appears to depress the immune response to malignant growths in exposed tissue. The length of time a person continues to smoke as well as the amount smoked increases the person's chances of developing lung cancer. If a person stops smoking, these chances steadily decrease as damage to the lungs is repaired and contaminant particles are gradually vacated. More recent work has shown that, across the developed world, almost 90% of lung cancer deaths are caused by smoking.[14] In addition, there is evidence that lung cancer in never-smokers has a better prognosis than in smokers,[15] and that patients who smoke at the time of diagnosis have shorter survival than those who have quit.[16] Passive smoking—the inhalation of smoke from another's smoking— is claimed to be a cause of lung cancer in non-smokers. Studies from the USA (1986,[17][18] 1992,[19] 1997,[20] 2001,[21] 2003[22]), Europe (1998[23]), the UK (1998[24][25]), and Australia (1997[26]) have consistently shown a significant increase in relative risk among those exposed to passive smoke.
In 1993, the United States Environmental Protection Agency (EPA) claimed that about 3,000 lung cancer-related deaths a year were caused by passive smoking. However, since this report was based on a study that was alleged to be heavily biased and was ruled by a federal judge to be "unscientific", the EPA report was declared null and void by a federal judge in 1998[27][28].
Percentage of lung cancer deaths attributable to smoking in the developed world 35-69 years 70 years+ All ages
Men 93.9% 90.3% 92.5%
Women 68.8% 68.9% 68.8%
Both 88.7% 84.3% 86.6%
The extensive attempts made by Philip Morris to delay the release of the 1997 IARC study, to affect the wording of its conclusions, to neutralise its negative results for their business, and to counteract its impact on public and policymakers' opinion have been documented by Ong & Glantz in The Lancet journal.[29] Their work was based on 32 million pages of documents made public as part of the settlement of the 1998 legal case of State of Minnesota and Blue Cross/Blue Shield of Minnesota vs Philip Morris Inc, et al. and available at Philip Morris' own website.[30]
Recent investigation of sidestream smoke suggests it is more dangerous than direct smoke inhalation.[31]
Asbestos
Asbestos can cause a variety of lung diseases. It increases the risk of developing lung cancer. There is a synergistic effect between tobacco smoking and asbestos in the formation of lung cancer.[32]
Asbestos can also cause cancer of the pleura, called mesothelioma (which is distinct from lung cancer).
Radon gas
Radon is a colorless and odourless gas generated by the breakdown of radioactive radium, which in turn is the decay product of uranium, found in the earth's crust. The radiation decay products ionize genetic material, causing mutations that sometimes turn cancerous. Radon exposure is the second major cause of lung cancer after smoking.[8]
Radon gas levels vary by locality and the composition of the underlying soil and rocks. For example, in areas such as Cornwall in the UK (which has granite as substrata), radon gas is a major problem, and buildings have to be force-ventilated with fans to lower radon gas concentrations. The United States Environmental Protection Agency (EPA) estimates that one in 15 homes in the USA has radon levels above the recommended guideline of 4 picoCuries per liter (pCi/L).[33] Iowa has the highest average radon concentration in the United States; studies performed there have demonstrated a 50% increased lung cancer risk with prolonged radon exposure above the EPA's action level of 4 pCi/L.[34][35]
Genetics and viruses
Oncogenes are genes that are believed make people more susceptible to cancer. Proto-oncogenes are believed to turn into oncogenes when exposed to particular carcinogens.[36] Viruses are known to cause lung cancer in animals[37][38] and recent evidence suggests similar potential in humans.[39][40]
Diagnosis
Chest x-ray showing lung cancer in the left lung.Performing a chest x-ray is the first step if a patient reports symptoms that may be suggestive of lung cancer. This may reveal an obvious mass, widening of the mediastinum (suggestive of spread to lymph nodes there), atelectasis (collapse), consolidation (infection) and pleural effusion. If there are no X-ray findings but the suspicion is high (e.g. a heavy smoker with blood-stained sputum), bronchoscopy and/or a CT scan may provide the necessary information. In any case, bronchoscopy or CT-guided biopsy is often necessary to identify the tumor type.[12]
CT scan showing lung cancer in the left lung.The differential diagnosis for patients who present with abnormalities on chest x-ray includes lung cancer, as well as other nonmalignant diseases. These include infectious causes such as tuberculosis or pneumonia, or inflammatory conditions such as sarcoidosis. These diseases can result in mediastinal lymphadenopathy or lung nodules, and sometimes mimic lung cancers.[13]
Types
There are two main types of lung cancer categorized by the size and appearance of the malignant cells seen by a histopathologist under a microscope: non-small cell (80%) and small-cell (roughly 20%) lung cancer.[12] This classification although based on simple pathomorphological criteria has very important implications for clinical management and prognosis of the disease.
Non-small cell lung cancer
The non-small cell lung cancers are grouped together because their prognosis and management are roughly identical. When it cannot be subtyped, it is frequently coded to 8046/3. The subtypes are:
Squamous cell carcinoma, accounting for 29% of lung cancers,[12] also starts in the larger bronchi but grows slower. This means that the size of these tumours varies on diagnosis.
Adenocarcinoma is the most common subtype of NSCLC, accounting for 32% of lung cancers.[12] It is a form which starts near the gas-exchanging surface of the lung. Most cases of adenocarcinoma are associated with smoking. However, among people who have never smoked ("never-smokers"), adenocarcinoma is the most common form of lung cancer.[41] A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have different responses to treatment.[42]
Large cell carcinoma is a fast-growing form, accounting for 9% of lung cancers,[12] that grows near the surface of the lung.
Small cell lung cancer
Small cell lung carcinoma (microscopic view of a core needle biopsy)SCLC (also called "oat cell carcinoma") is the less common form of lung cancer. It tends to start in the larger breathing tubes and grows rapidly becoming quite large. The oncogene most commonly involved is L-myc. The "oat" cell contains dense neurosecretory granules which give this an endocrine/paraneoplastic syndrome association. It is initially more sensitive to chemotherapy, but ultimately carries a worse prognosis and is often metastatic at presentation. This type of lung cancer is strongly associated with smoking.
Other types
Carcinoid
Adenoid cystic carcinoma
Cylindroma
Mucoepidermoid carcinoma
Metastatic cancers
The lung is a common place for metastasis from tumors in other parts of the body. These cancers, however, are identified by the site of origin, i.e., a breast cancer metastasis to the lung is still known as breast cancer. The adrenal glands, liver, brain, and bone are the most common sites of metastasis from primary lung cancer itself.
Lung cancer staging
Lung cancer staging is an assessment of the degree of spread of the cancer from its original source. It is an important contributor to the prognosis and potential treatment of lung cancer.
Non-small cell lung cancer is staged from IA ("one A", best prognosis) to IV ("four", worst prognosis).
See non-small cell lung cancer staging.[43]
Small cell lung cancer is classified as limited stage if it is confined to one half of the chest and within the scope of a single radiotherapy field. Otherwise it extensive stage.[44]
Treatment
Treatment for lung cancer depends on the cancer's specific cell type, how far it has spread, and the patient's performance status. Common treatments include surgery, chemotherapy, and radiation therapy. The 5-year overall survival rate is 14%.[12]
Surgery
If investigations confirm lung cancer, CT scan and often positron emission tomography (PET) are used to determine whether the disease is localised and amenable to surgery or whether it has spread to the point where it cannot be cured surgically.
Blood tests and spirometry (lung function testing) are also necessary to assess whether the patient is well enough to be operated on. If spirometry reveals a very poor respiratory reserve, as may occur in chronic smokers, surgery may be contraindicated.
Surgery itself has an overall operative death rate of 5%, depending on the patient's lung function and other risk factors.[45] Surgery is usually only an option in non-small cell lung cancer limited to one lung, up to stage IIIA. This is assessed with medical imaging (computed tomography, positron emission tomography). A sufficient pre-operative respiratory reserve must be present to allow adequate lung function after the tissue is removed.
Procedures include wedge excision (removal of part of a lobe), lobectomy (one lobe), bilobectomy (two lobes) or pneumonectomy (whole lung). In patients with adequate respiratory reserve, lobectomy is the preferred option, as this minimizes the chance of local recurrence. If the patient does not have enough functional lung for this, wedge excision may be performed.[46] Radioactive iodine brachytherapy at the margins of wedge excision may reduce recurrence to that of lobectomy.[47]
Chemotherapy
Small cell lung cancer is treated primarily with chemotherapy, as surgery has no demonstrable influence on survival. Primary chemotherapy is also given in metastatic non-small cell lung cancer.
The combination regimen depends on the tumour type:
NSCLC: cisplatin or carboplatin, in combination with gemcitabine, paclitaxel, docetaxel, etoposide or vinorelbine.[48]
SCLC: cisplatin and etoposide are most commonly used.[49] Combinations with carboplatin, gemcitabine, paclitaxel, vinorelbine, topotecan and irinotecan are also used.[50][51]
Adjuvant chemotherapy
Adjuvant chemotherapy refers to the use of chemotherapy after surgery to improve the outcome. During surgery, samples are taken from the lymph nodes. If these samples contain cancer, then the patient has stage II or III disease. In this situation, adjuvant chemotherapy may improve survival by up to 15%.[52][53]
Standard practice is to offer platinum-based chemotherapy (e.g. cisplatin and vinorelbine).[54]
Adjuvant chemotherapy for patients with stage IB cancer is controversial as clinical trials have not clearly demonstrated a survival benefit.[55][56]
Trials of preoperative chemotherapy (neoadjuvant chemotherapy) in resectable non-small cell lung cancer have been inconclusive.[57]
Targeted therapy
In recent years, various molecular targeted therapies have been developed for the treatment of advanced lung cancer. Gefitinib (Iressa) is one such drug, which targets the tyrosine kinase domain of the epidermal growth factor receptor (EGF-R) which is expressed in many cases of non-small cell lung cancer. However despite an exciting start it was not shown to increase survival, although females, Asians, non-smokers and those with the bronchioloalveolar carcinoma cell type appear to be deriving most benefit from gefitinib.[42]
Erlotinib (Tarceva), another tyrosine kinase inhibitor, has been shown to increase survival in lung cancer patients and has recently been approved by the FDA for second-line treatment of advanced non-small cell lung cancer. [Similar to gefitinib, it appeared to work best in females, Asians, non-smokers and those with the bronchioloalveolar carcinoma cell type.]
A number of targeted agents are at the early stages of clinical research, such as cyclo-oxygenase-2 (COX-2) inhibitors, the apoptosis promoter exisulind,[58] proteasome inhibitors, bexarotene (Targretin) and vaccines.[59]
Treatment of lung cancer is evolving.[60][61][62]
Radiotherapy
Radiotherapy is often given together with chemotherapy, and may be used with curative intent in patients who are not eligible for surgery. A radiation dose of 40 or more Gy in many fractions is commonly used with curative intent in non-small cell lung cancer; typically in North America, the dose prescribed is 60 or 66 Gy in 30 to 33 fractions given once daily, 5 days a week, for 6 to 6½ weeks. For small cell lung cancer cases that are potentially curable, in addition to chemotherapy, chest radiation is often recommended. For these small cell lung cancer cases, chest radiation doses of 40 Gy or more in many fractions are commonly given; typically in North America, the dose prescribed is 45 to 50 Gy and can be given in either once daily treatments for 5 weeks or twice daily treatments for 3 weeks.[63]
For both non-small cell lung cancer and small cell lung cancer patients, radiation of disease in the chest to smaller doses (typically 20 Gy in 5 fractions) may be used for symptom control.
Interventional radiology
Radiofrequency ablation is increasing in popularity for this condition as it is nontoxic and causes very little pain. It seems especially effective when combined with chemotherapy as it catches the cells deeper inside a tumor—the ones difficult to get with chemotherapy due to reduced blood supply to the center of the tumor. It is done by inserting a small heat probe into the tumor to kill the tumor cells.[64]
Prognosis
For non-small cell lung cancer, prognosis is poor. Following complete surgical resection of stage IA disease, five-year survival is 67%. With stage IB disease, five-year survival is 57%.[65] The 5-year survival rate of patients with stage IV NSCLC is about 1%.[66]
See non-small cell lung cancer staging.
For small cell lung carcinoma, prognosis is also poor. The overall five-year survival for patients with SCLC is about 5%.[12] Patients with extensive-stage SCLC have an average five-year survival rate of less than 1%. The median survival time for limited-stage disease is 20 months, with a five-year survival rate of 20%.[66]
See Manchester score.
Epidemiology
Lung cancer distribution in the United States.The population segment most likely to develop lung cancer is the over-fifties who also have a history of smoking. Lung cancer is the second most commonly occurring form of cancer in most western countries, and it is the leading cancer-related cause of death for men and women. In the US, 175,000 new cases are expected in 2006:[67] 90,700 in men and 80,000 in women. Although the rate of men dying from lung cancer is declining in western countries, it is actually increasing for women due to the increased takeup of smoking by this group. Among lifetime non-smokers, men who have never smoked have higher age-standardized lung cancer death rates than women. Of the 80,000 women who are diagnosed with lung cancer in 2006, approximately 70,000 are expected to die from it.[68]
Lung cancer was extremely rare prior to the advent of cigarette smoking. In 1878, malignant lung tumors made up only 1% of all cancers seen at autopsy; this had risen to 10-15% by the early 1900s.[69] Case reports in the medical literature numbered only 374 worldwide in 1912.[70] The British Doctors Study, published in the 1950s, first offered solid epidemiological evidence on the link between lung cancer and smoking.
Not all cases of lung cancer are due to smoking, but the role of passive smoking is increasingly being recognized as a risk factor for lung cancer, leading to policy interventions to decrease undesired exposure of non-smokers to others' tobacco smoke. Emissions from automobiles, factories and power plants also pose potential risks.[9][11][71]
Eastern Europe has the highest lung cancer mortality among men, while northern Europe and the USA have the highest mortality among women. Lung cancer incidence is less common in developing countries.[72]
Prevention
Primary prevention
Prevention is the most cost-effective means of fighting lung cancer on the national and global scales. While in most countries industrial and domestic carcinogens have been identified and banned, tobacco smoking is still widespread. Eliminating tobacco smoking is a primary goal in the prevention of lung cancer, and smoking cessation is an important preventative tool in this process.[73]
Policy interventions to decrease passive smoking (e.g. in restaurants and workplaces) have become more common in various Western countries, with California taking a lead in banning smoking in public establishments in 1998, Ireland playing a similar role in Europe in 2004, followed by Italy and Norway in 2005 and Scotland as well as several others in 2006 New Zealand has also recently banned smoking in public places. (See Smoking ban and list of smoking bans).
Only the Asian state of Bhutan has a complete smoking ban (since 2005). In many countries pressure groups are campaigning for similar bans. Arguments cited against such bans are criminalisation of smoking, increased risk of smuggling and the risk that such a ban cannot be enforced.
Screening
Main article: lung cancer screening
Screening refers to the use of medical tests to detect disease in asymptomatic people. Possible screening tests for lung cancer include chest x-ray or computed tomography (CT) of the chest.
So far, screening programs for lung cancer have not demonstrated any clear benefit. However randomized controlled studies are underway in this area to see if decreased long-term mortality can be directly observed from CT screening.[74]
Current research indicates that the factor with the greatest impact on risk of lung cancer is long-term exposure to inhaled carcinogens, especially tobacco smoke.[4] While some people who have never smoked do still get lung cancer, this appears to be due to a combination of genetic factors[5] and exposure to secondhand smoke.[6][7] Radon gas[8] and air pollution may also contribute to the development of lung cancer.[9][10][11]
Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Treatments include surgery, chemotherapy, and radiotherapy.[12]
Signs and symptoms
Symptoms that suggest lung cancer include:[12]
dyspnea (shortness of breath)
hemoptysis (coughing up blood)
chronic coughing or change in regular coughing pattern
wheezing
chest pain or pain in the abdomen
cachexia (weight loss), fatigue and loss of appetite
dysphonia (hoarse voice)
clubbing of the fingernails (uncommon)
difficulty swallowing
If the cancer grows in the airway, it may obstruct airflow, causing breathing difficulties. This can lead to accumulation of secretions behind the blockage, predisposing the patient to pneumonia.
Many lung cancers have a rich blood supply. The surface of the cancer may be fragile, leading to bleeding from the cancer into the airway. This blood may subsequently be coughed up.
Depending on the type of tumor, so-called paraneoplastic phenomena may initially attract attention to the disease. In lung cancer, this may be Lambert-Eaton myasthenic syndrome (muscle weakness due to auto-antibodies), hypercalcemia and SIADH. Tumors in the top (apex) of the lung, known as Pancoast tumors, may invade the local part of the sympathetic nervous system, leading to changed sweating patterns and eye muscle problems (a combination known as Horner's syndrome), as well as muscle weakness in the hands due to invasion of the brachial plexus.
In many patients, the cancer has already spread beyond the original site by the time they have symptoms and seek medical attention. Common sites of metastasis include the bone, such as the spine (causing back pain and occasionally spinal cord compression), the liver and the brain.
About 10% of people with lung cancer do not have symptoms of it at the time of diagnosis; these cancers are usually found on routine chest x-rays.[12]
Unfortunately, many of the symptoms of lung cancer (bone pain, fever, weight loss ) are nonspecific and in the elderly may be attributed to comorbid illness. [13]
Causes
Exposure to carcinogens in tobacco smoke causes cumulative changes to the tissue lining the bronchi of the lungs (the bronchial mucous membrane) and more tissue gets damaged until a tumour develops.
There are four major causes of lung cancer (and cancer in general):
Carcinogens such as those in tobacco smoke
Radiation exposure
Genetic susceptibility
Viral infection
The role of smoking
The incidence of lung cancer is highly correlated with smoking. Source:NIH.Smoking, particularly of cigarettes, is by far the main contributor to lung cancer, which at least in theory makes it one of the easiest diseases to prevent. In the United States, smoking is estimated to account for 87% of lung cancer cases (90% in men and 79% in women), and in the UK for 90%. Cigarette smoke contains 19 known carcinogens[4] including radioisotopes from the radon decay sequence, nitrosamine, and benzopyrene. Additionally, nicotine appears to depress the immune response to malignant growths in exposed tissue. The length of time a person continues to smoke as well as the amount smoked increases the person's chances of developing lung cancer. If a person stops smoking, these chances steadily decrease as damage to the lungs is repaired and contaminant particles are gradually vacated. More recent work has shown that, across the developed world, almost 90% of lung cancer deaths are caused by smoking.[14] In addition, there is evidence that lung cancer in never-smokers has a better prognosis than in smokers,[15] and that patients who smoke at the time of diagnosis have shorter survival than those who have quit.[16] Passive smoking—the inhalation of smoke from another's smoking— is claimed to be a cause of lung cancer in non-smokers. Studies from the USA (1986,[17][18] 1992,[19] 1997,[20] 2001,[21] 2003[22]), Europe (1998[23]), the UK (1998[24][25]), and Australia (1997[26]) have consistently shown a significant increase in relative risk among those exposed to passive smoke.
In 1993, the United States Environmental Protection Agency (EPA) claimed that about 3,000 lung cancer-related deaths a year were caused by passive smoking. However, since this report was based on a study that was alleged to be heavily biased and was ruled by a federal judge to be "unscientific", the EPA report was declared null and void by a federal judge in 1998[27][28].
Percentage of lung cancer deaths attributable to smoking in the developed world 35-69 years 70 years+ All ages
Men 93.9% 90.3% 92.5%
Women 68.8% 68.9% 68.8%
Both 88.7% 84.3% 86.6%
The extensive attempts made by Philip Morris to delay the release of the 1997 IARC study, to affect the wording of its conclusions, to neutralise its negative results for their business, and to counteract its impact on public and policymakers' opinion have been documented by Ong & Glantz in The Lancet journal.[29] Their work was based on 32 million pages of documents made public as part of the settlement of the 1998 legal case of State of Minnesota and Blue Cross/Blue Shield of Minnesota vs Philip Morris Inc, et al. and available at Philip Morris' own website.[30]
Recent investigation of sidestream smoke suggests it is more dangerous than direct smoke inhalation.[31]
Asbestos
Asbestos can cause a variety of lung diseases. It increases the risk of developing lung cancer. There is a synergistic effect between tobacco smoking and asbestos in the formation of lung cancer.[32]
Asbestos can also cause cancer of the pleura, called mesothelioma (which is distinct from lung cancer).
Radon gas
Radon is a colorless and odourless gas generated by the breakdown of radioactive radium, which in turn is the decay product of uranium, found in the earth's crust. The radiation decay products ionize genetic material, causing mutations that sometimes turn cancerous. Radon exposure is the second major cause of lung cancer after smoking.[8]
Radon gas levels vary by locality and the composition of the underlying soil and rocks. For example, in areas such as Cornwall in the UK (which has granite as substrata), radon gas is a major problem, and buildings have to be force-ventilated with fans to lower radon gas concentrations. The United States Environmental Protection Agency (EPA) estimates that one in 15 homes in the USA has radon levels above the recommended guideline of 4 picoCuries per liter (pCi/L).[33] Iowa has the highest average radon concentration in the United States; studies performed there have demonstrated a 50% increased lung cancer risk with prolonged radon exposure above the EPA's action level of 4 pCi/L.[34][35]
Genetics and viruses
Oncogenes are genes that are believed make people more susceptible to cancer. Proto-oncogenes are believed to turn into oncogenes when exposed to particular carcinogens.[36] Viruses are known to cause lung cancer in animals[37][38] and recent evidence suggests similar potential in humans.[39][40]
Diagnosis
Chest x-ray showing lung cancer in the left lung.Performing a chest x-ray is the first step if a patient reports symptoms that may be suggestive of lung cancer. This may reveal an obvious mass, widening of the mediastinum (suggestive of spread to lymph nodes there), atelectasis (collapse), consolidation (infection) and pleural effusion. If there are no X-ray findings but the suspicion is high (e.g. a heavy smoker with blood-stained sputum), bronchoscopy and/or a CT scan may provide the necessary information. In any case, bronchoscopy or CT-guided biopsy is often necessary to identify the tumor type.[12]
CT scan showing lung cancer in the left lung.The differential diagnosis for patients who present with abnormalities on chest x-ray includes lung cancer, as well as other nonmalignant diseases. These include infectious causes such as tuberculosis or pneumonia, or inflammatory conditions such as sarcoidosis. These diseases can result in mediastinal lymphadenopathy or lung nodules, and sometimes mimic lung cancers.[13]
Types
There are two main types of lung cancer categorized by the size and appearance of the malignant cells seen by a histopathologist under a microscope: non-small cell (80%) and small-cell (roughly 20%) lung cancer.[12] This classification although based on simple pathomorphological criteria has very important implications for clinical management and prognosis of the disease.
Non-small cell lung cancer
The non-small cell lung cancers are grouped together because their prognosis and management are roughly identical. When it cannot be subtyped, it is frequently coded to 8046/3. The subtypes are:
Squamous cell carcinoma, accounting for 29% of lung cancers,[12] also starts in the larger bronchi but grows slower. This means that the size of these tumours varies on diagnosis.
Adenocarcinoma is the most common subtype of NSCLC, accounting for 32% of lung cancers.[12] It is a form which starts near the gas-exchanging surface of the lung. Most cases of adenocarcinoma are associated with smoking. However, among people who have never smoked ("never-smokers"), adenocarcinoma is the most common form of lung cancer.[41] A subtype of adenocarcinoma, the bronchioloalveolar carcinoma, is more common in female never-smokers, and may have different responses to treatment.[42]
Large cell carcinoma is a fast-growing form, accounting for 9% of lung cancers,[12] that grows near the surface of the lung.
Small cell lung cancer
Small cell lung carcinoma (microscopic view of a core needle biopsy)SCLC (also called "oat cell carcinoma") is the less common form of lung cancer. It tends to start in the larger breathing tubes and grows rapidly becoming quite large. The oncogene most commonly involved is L-myc. The "oat" cell contains dense neurosecretory granules which give this an endocrine/paraneoplastic syndrome association. It is initially more sensitive to chemotherapy, but ultimately carries a worse prognosis and is often metastatic at presentation. This type of lung cancer is strongly associated with smoking.
Other types
Carcinoid
Adenoid cystic carcinoma
Cylindroma
Mucoepidermoid carcinoma
Metastatic cancers
The lung is a common place for metastasis from tumors in other parts of the body. These cancers, however, are identified by the site of origin, i.e., a breast cancer metastasis to the lung is still known as breast cancer. The adrenal glands, liver, brain, and bone are the most common sites of metastasis from primary lung cancer itself.
Lung cancer staging
Lung cancer staging is an assessment of the degree of spread of the cancer from its original source. It is an important contributor to the prognosis and potential treatment of lung cancer.
Non-small cell lung cancer is staged from IA ("one A", best prognosis) to IV ("four", worst prognosis).
See non-small cell lung cancer staging.[43]
Small cell lung cancer is classified as limited stage if it is confined to one half of the chest and within the scope of a single radiotherapy field. Otherwise it extensive stage.[44]
Treatment
Treatment for lung cancer depends on the cancer's specific cell type, how far it has spread, and the patient's performance status. Common treatments include surgery, chemotherapy, and radiation therapy. The 5-year overall survival rate is 14%.[12]
Surgery
If investigations confirm lung cancer, CT scan and often positron emission tomography (PET) are used to determine whether the disease is localised and amenable to surgery or whether it has spread to the point where it cannot be cured surgically.
Blood tests and spirometry (lung function testing) are also necessary to assess whether the patient is well enough to be operated on. If spirometry reveals a very poor respiratory reserve, as may occur in chronic smokers, surgery may be contraindicated.
Surgery itself has an overall operative death rate of 5%, depending on the patient's lung function and other risk factors.[45] Surgery is usually only an option in non-small cell lung cancer limited to one lung, up to stage IIIA. This is assessed with medical imaging (computed tomography, positron emission tomography). A sufficient pre-operative respiratory reserve must be present to allow adequate lung function after the tissue is removed.
Procedures include wedge excision (removal of part of a lobe), lobectomy (one lobe), bilobectomy (two lobes) or pneumonectomy (whole lung). In patients with adequate respiratory reserve, lobectomy is the preferred option, as this minimizes the chance of local recurrence. If the patient does not have enough functional lung for this, wedge excision may be performed.[46] Radioactive iodine brachytherapy at the margins of wedge excision may reduce recurrence to that of lobectomy.[47]
Chemotherapy
Small cell lung cancer is treated primarily with chemotherapy, as surgery has no demonstrable influence on survival. Primary chemotherapy is also given in metastatic non-small cell lung cancer.
The combination regimen depends on the tumour type:
NSCLC: cisplatin or carboplatin, in combination with gemcitabine, paclitaxel, docetaxel, etoposide or vinorelbine.[48]
SCLC: cisplatin and etoposide are most commonly used.[49] Combinations with carboplatin, gemcitabine, paclitaxel, vinorelbine, topotecan and irinotecan are also used.[50][51]
Adjuvant chemotherapy
Adjuvant chemotherapy refers to the use of chemotherapy after surgery to improve the outcome. During surgery, samples are taken from the lymph nodes. If these samples contain cancer, then the patient has stage II or III disease. In this situation, adjuvant chemotherapy may improve survival by up to 15%.[52][53]
Standard practice is to offer platinum-based chemotherapy (e.g. cisplatin and vinorelbine).[54]
Adjuvant chemotherapy for patients with stage IB cancer is controversial as clinical trials have not clearly demonstrated a survival benefit.[55][56]
Trials of preoperative chemotherapy (neoadjuvant chemotherapy) in resectable non-small cell lung cancer have been inconclusive.[57]
Targeted therapy
In recent years, various molecular targeted therapies have been developed for the treatment of advanced lung cancer. Gefitinib (Iressa) is one such drug, which targets the tyrosine kinase domain of the epidermal growth factor receptor (EGF-R) which is expressed in many cases of non-small cell lung cancer. However despite an exciting start it was not shown to increase survival, although females, Asians, non-smokers and those with the bronchioloalveolar carcinoma cell type appear to be deriving most benefit from gefitinib.[42]
Erlotinib (Tarceva), another tyrosine kinase inhibitor, has been shown to increase survival in lung cancer patients and has recently been approved by the FDA for second-line treatment of advanced non-small cell lung cancer. [Similar to gefitinib, it appeared to work best in females, Asians, non-smokers and those with the bronchioloalveolar carcinoma cell type.]
A number of targeted agents are at the early stages of clinical research, such as cyclo-oxygenase-2 (COX-2) inhibitors, the apoptosis promoter exisulind,[58] proteasome inhibitors, bexarotene (Targretin) and vaccines.[59]
Treatment of lung cancer is evolving.[60][61][62]
Radiotherapy
Radiotherapy is often given together with chemotherapy, and may be used with curative intent in patients who are not eligible for surgery. A radiation dose of 40 or more Gy in many fractions is commonly used with curative intent in non-small cell lung cancer; typically in North America, the dose prescribed is 60 or 66 Gy in 30 to 33 fractions given once daily, 5 days a week, for 6 to 6½ weeks. For small cell lung cancer cases that are potentially curable, in addition to chemotherapy, chest radiation is often recommended. For these small cell lung cancer cases, chest radiation doses of 40 Gy or more in many fractions are commonly given; typically in North America, the dose prescribed is 45 to 50 Gy and can be given in either once daily treatments for 5 weeks or twice daily treatments for 3 weeks.[63]
For both non-small cell lung cancer and small cell lung cancer patients, radiation of disease in the chest to smaller doses (typically 20 Gy in 5 fractions) may be used for symptom control.
Interventional radiology
Radiofrequency ablation is increasing in popularity for this condition as it is nontoxic and causes very little pain. It seems especially effective when combined with chemotherapy as it catches the cells deeper inside a tumor—the ones difficult to get with chemotherapy due to reduced blood supply to the center of the tumor. It is done by inserting a small heat probe into the tumor to kill the tumor cells.[64]
Prognosis
For non-small cell lung cancer, prognosis is poor. Following complete surgical resection of stage IA disease, five-year survival is 67%. With stage IB disease, five-year survival is 57%.[65] The 5-year survival rate of patients with stage IV NSCLC is about 1%.[66]
See non-small cell lung cancer staging.
For small cell lung carcinoma, prognosis is also poor. The overall five-year survival for patients with SCLC is about 5%.[12] Patients with extensive-stage SCLC have an average five-year survival rate of less than 1%. The median survival time for limited-stage disease is 20 months, with a five-year survival rate of 20%.[66]
See Manchester score.
Epidemiology
Lung cancer distribution in the United States.The population segment most likely to develop lung cancer is the over-fifties who also have a history of smoking. Lung cancer is the second most commonly occurring form of cancer in most western countries, and it is the leading cancer-related cause of death for men and women. In the US, 175,000 new cases are expected in 2006:[67] 90,700 in men and 80,000 in women. Although the rate of men dying from lung cancer is declining in western countries, it is actually increasing for women due to the increased takeup of smoking by this group. Among lifetime non-smokers, men who have never smoked have higher age-standardized lung cancer death rates than women. Of the 80,000 women who are diagnosed with lung cancer in 2006, approximately 70,000 are expected to die from it.[68]
Lung cancer was extremely rare prior to the advent of cigarette smoking. In 1878, malignant lung tumors made up only 1% of all cancers seen at autopsy; this had risen to 10-15% by the early 1900s.[69] Case reports in the medical literature numbered only 374 worldwide in 1912.[70] The British Doctors Study, published in the 1950s, first offered solid epidemiological evidence on the link between lung cancer and smoking.
Not all cases of lung cancer are due to smoking, but the role of passive smoking is increasingly being recognized as a risk factor for lung cancer, leading to policy interventions to decrease undesired exposure of non-smokers to others' tobacco smoke. Emissions from automobiles, factories and power plants also pose potential risks.[9][11][71]
Eastern Europe has the highest lung cancer mortality among men, while northern Europe and the USA have the highest mortality among women. Lung cancer incidence is less common in developing countries.[72]
Prevention
Primary prevention
Prevention is the most cost-effective means of fighting lung cancer on the national and global scales. While in most countries industrial and domestic carcinogens have been identified and banned, tobacco smoking is still widespread. Eliminating tobacco smoking is a primary goal in the prevention of lung cancer, and smoking cessation is an important preventative tool in this process.[73]
Policy interventions to decrease passive smoking (e.g. in restaurants and workplaces) have become more common in various Western countries, with California taking a lead in banning smoking in public establishments in 1998, Ireland playing a similar role in Europe in 2004, followed by Italy and Norway in 2005 and Scotland as well as several others in 2006 New Zealand has also recently banned smoking in public places. (See Smoking ban and list of smoking bans).
Only the Asian state of Bhutan has a complete smoking ban (since 2005). In many countries pressure groups are campaigning for similar bans. Arguments cited against such bans are criminalisation of smoking, increased risk of smuggling and the risk that such a ban cannot be enforced.
Screening
Main article: lung cancer screening
Screening refers to the use of medical tests to detect disease in asymptomatic people. Possible screening tests for lung cancer include chest x-ray or computed tomography (CT) of the chest.
So far, screening programs for lung cancer have not demonstrated any clear benefit. However randomized controlled studies are underway in this area to see if decreased long-term mortality can be directly observed from CT screening.[74]
INVESTMENT
Investment
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Finance
Financial Markets
Bond market
Stock (Equities) Market
Forex market
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Market Participants
Investors
Speculators
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Corporate finance
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Capital budgeting
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Accounting
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Credit and Debt
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Loan
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Stock market crash
v d e
“Invest” redirects here. For other uses, see Invest (disambiguation).
Investment or investing[1] is a term with several closely-related meanings in business management, finance and economics, related to saving or deferring consumption. An asset is usually purchased, or equivalently a deposit is made in a bank, in hopes of getting a future return or interest from it. Literally, the word means the "action of putting something in to somewhere else" (perhaps originally related to a person's garment or 'vestment').
Contents [hide]
1 Types of investment
1.1 Business Management
1.2 Economics
1.3 Finance
1.4 Personal finance
1.5 Real estate
1.5.1 Residential Real Estate
1.5.2 Commercial Real Estate
2 See also
3 Notes
4 External links
[edit] Types of investment
The term "investment" is used differently in economics and in finance. Economists refer to a real investment (such as a machine or a house), while financial economists refer to a financial asset, such as money that is put into a bank or the market, which may then be used to buy a real asset.
[edit] Business Management
The investment decision (also known as capital budgeting) is one of the fundamental decisions of business management: managers determine the assets that the business enterprise obtains. These assets may be physical (such as buildings or machinery), intangible (such as patents, software, goodwill), or financial (see below). The manager must assess whether the net present value of the investment to the enterprise is positive; the net present value is calculated using the enterprise's marginal cost of capital.
[edit] Economics
In economics, investment is the production per unit time of goods which are not consumed but are to be used for future production. Examples include tangibles (such as building a railroad or factory) and intangibles (such as a year of schooling or on-the-job training). In measures of national income and output, gross investment I is also a component of Gross domestic product (GDP), given in the formula GDP = C + I + G + NX. I is divided into non-residential investment (such as factories) and residential investment (new houses). "Net" investment deducts depreciation from gross investment. It is the value of the net increase in the capital stock per year.
Investment, as production over a period of time ("per year"), is not capital. The time dimension of investment makes it a flow. By contrast, capital is a stock, that is, an accumulation measurable at a point in time (say December 31st).
Investment is often modelled as a function of income and interest rates, given by the relation I = f(Y, r). An increase in income encourages higher investment, whereas a higher interest rate may discourage investment as it becomes more costly to borrow money. Even if a firm chooses to use its own funds in an investment, the interest rate represents an opportunity cost of investing those funds rather than loaning them out for interest.
[edit] Finance
In finance, investment is buying securities or other monetary or paper (financial) assets in the money markets or capital markets, or in fairly liquid real assets, such as gold, real estate, or collectibles. Valuation is the method for assessing whether a potential investment is worth its price.
Types of financial investments include shares, other equity investment, and bonds (including bonds denominated in foreign currencies). These financial assets are then expected to provide income or positive future cash flows, and may increase or decrease in value giving the investor capital gains or losses.
Trades in contingent claims or derivative securities do not necessarily have future positive expected cash flows, and so are not considered assets, or strictly speaking, securities or investments. Nevertheless, since their cash flows are closely related to (or derived from) those of specific securities, they are often studied as or treated as investments.
Investments are often made indirectly through intermediaries, such as banks, mutual funds, pension funds, insurance companies, collective investment schemes, and investment clubs. Though their legal and procedural details differ, an intermediary generally makes an investment using money from many individuals, each of whom receives a claim on the intermediary.
[edit] Personal finance
Within personal finance, money used to purchase shares, put in a collective investment scheme or used to buy any asset where there is an element of capital risk is deemed an investment. Saving within personal finance refers to money put aside, normally on a regular basis. This distinction is important, as investment risk can cause a capital loss when an investment is realized, unlike saving(s) where the more limited risk is cash devaluing due to inflation.
In many instances the terms saving and investment are used interchangeably, which confuses this distinction. For example many deposit accounts are labeled as investment accounts by banks for marketing purposes. Whether an asset is a saving(s) or an investment depends on where the money is invested: if it is cash then it is savings, if its value can fluctuate then it is investment.
[edit] Real estate
In real estate, investment is money used to purchase property for the sole purpose of holding or leasing for income and where there is an element of capital risk. Unlike other economic or financial investment, real estate is purchased. The seller is also called a Vendor and normally the purchaser is called a Buyer.
[edit] Residential Real Estate
The most common form of real estate investment as it includes the property purchased as peoples houses. In many cases the Buyer does not have the full purchase price for a property and must engage a lender such as a Bank, Finance company or Private Lender. Different countries have their individual normal lending levels, but usually they will fall into the range of 70-90% of the purchase price. Against other types of real estate, residential real estate is the least risky.
[edit] Commercial Real Estate
Commercial real estate is the owning of a building small or large warehouse a company rents from so that it can conduct its business. Due to the higher risk of Commercial real estate, lending rates of banks and other lenders are lower and often fall in the range of 50-70%.
[edit] See also
Appreciation
Capital accumulation
Capital (economics)
Diversifying investment
Divestment
Financial economics
Foreign direct investment
Gold as an investment
Investor profile
Investor relations
Investment-specific technological progress
Kelly Criterion For Stock Market
Market trends
Megaproject
Over-investing
Philatelic investment
Regulation Fair Disclosure
Rate of return
Saving
Silver as an investment
Speculation
Stock trader
Value investing
List of marketing topics
List of management topics
List of economics topics
List of accounting topics
List of finance topics
List of economists
List of financial services companies (by country)
From Wikipedia, the free encyclopedia
(Redirected from Investing)
Jump to: navigation, search
Finance
Financial Markets
Bond market
Stock (Equities) Market
Forex market
Derivatives market
Commodities market
Spot (cash) Market
OTC market
Real Estate market
Market Participants
Investors
Speculators
Institutional Investors
Corporate finance
Structured finance
Capital budgeting
Financial risk management
Mergers and Acquisitions
Accounting
Financial Statements
Auditing
Credit rating agency
Personal finance
Credit and Debt
Employment contract
Retirement
Financial planning
Public finance
Tax
Banks and Banking
Central Bank
List of banks
Deposits
Loan
Financial regulation
Finance designations
Accounting scandals
History of finance
Stock market bubble
Recession
Stock market crash
v d e
“Invest” redirects here. For other uses, see Invest (disambiguation).
Investment or investing[1] is a term with several closely-related meanings in business management, finance and economics, related to saving or deferring consumption. An asset is usually purchased, or equivalently a deposit is made in a bank, in hopes of getting a future return or interest from it. Literally, the word means the "action of putting something in to somewhere else" (perhaps originally related to a person's garment or 'vestment').
Contents [hide]
1 Types of investment
1.1 Business Management
1.2 Economics
1.3 Finance
1.4 Personal finance
1.5 Real estate
1.5.1 Residential Real Estate
1.5.2 Commercial Real Estate
2 See also
3 Notes
4 External links
[edit] Types of investment
The term "investment" is used differently in economics and in finance. Economists refer to a real investment (such as a machine or a house), while financial economists refer to a financial asset, such as money that is put into a bank or the market, which may then be used to buy a real asset.
[edit] Business Management
The investment decision (also known as capital budgeting) is one of the fundamental decisions of business management: managers determine the assets that the business enterprise obtains. These assets may be physical (such as buildings or machinery), intangible (such as patents, software, goodwill), or financial (see below). The manager must assess whether the net present value of the investment to the enterprise is positive; the net present value is calculated using the enterprise's marginal cost of capital.
[edit] Economics
In economics, investment is the production per unit time of goods which are not consumed but are to be used for future production. Examples include tangibles (such as building a railroad or factory) and intangibles (such as a year of schooling or on-the-job training). In measures of national income and output, gross investment I is also a component of Gross domestic product (GDP), given in the formula GDP = C + I + G + NX. I is divided into non-residential investment (such as factories) and residential investment (new houses). "Net" investment deducts depreciation from gross investment. It is the value of the net increase in the capital stock per year.
Investment, as production over a period of time ("per year"), is not capital. The time dimension of investment makes it a flow. By contrast, capital is a stock, that is, an accumulation measurable at a point in time (say December 31st).
Investment is often modelled as a function of income and interest rates, given by the relation I = f(Y, r). An increase in income encourages higher investment, whereas a higher interest rate may discourage investment as it becomes more costly to borrow money. Even if a firm chooses to use its own funds in an investment, the interest rate represents an opportunity cost of investing those funds rather than loaning them out for interest.
[edit] Finance
In finance, investment is buying securities or other monetary or paper (financial) assets in the money markets or capital markets, or in fairly liquid real assets, such as gold, real estate, or collectibles. Valuation is the method for assessing whether a potential investment is worth its price.
Types of financial investments include shares, other equity investment, and bonds (including bonds denominated in foreign currencies). These financial assets are then expected to provide income or positive future cash flows, and may increase or decrease in value giving the investor capital gains or losses.
Trades in contingent claims or derivative securities do not necessarily have future positive expected cash flows, and so are not considered assets, or strictly speaking, securities or investments. Nevertheless, since their cash flows are closely related to (or derived from) those of specific securities, they are often studied as or treated as investments.
Investments are often made indirectly through intermediaries, such as banks, mutual funds, pension funds, insurance companies, collective investment schemes, and investment clubs. Though their legal and procedural details differ, an intermediary generally makes an investment using money from many individuals, each of whom receives a claim on the intermediary.
[edit] Personal finance
Within personal finance, money used to purchase shares, put in a collective investment scheme or used to buy any asset where there is an element of capital risk is deemed an investment. Saving within personal finance refers to money put aside, normally on a regular basis. This distinction is important, as investment risk can cause a capital loss when an investment is realized, unlike saving(s) where the more limited risk is cash devaluing due to inflation.
In many instances the terms saving and investment are used interchangeably, which confuses this distinction. For example many deposit accounts are labeled as investment accounts by banks for marketing purposes. Whether an asset is a saving(s) or an investment depends on where the money is invested: if it is cash then it is savings, if its value can fluctuate then it is investment.
[edit] Real estate
In real estate, investment is money used to purchase property for the sole purpose of holding or leasing for income and where there is an element of capital risk. Unlike other economic or financial investment, real estate is purchased. The seller is also called a Vendor and normally the purchaser is called a Buyer.
[edit] Residential Real Estate
The most common form of real estate investment as it includes the property purchased as peoples houses. In many cases the Buyer does not have the full purchase price for a property and must engage a lender such as a Bank, Finance company or Private Lender. Different countries have their individual normal lending levels, but usually they will fall into the range of 70-90% of the purchase price. Against other types of real estate, residential real estate is the least risky.
[edit] Commercial Real Estate
Commercial real estate is the owning of a building small or large warehouse a company rents from so that it can conduct its business. Due to the higher risk of Commercial real estate, lending rates of banks and other lenders are lower and often fall in the range of 50-70%.
[edit] See also
Appreciation
Capital accumulation
Capital (economics)
Diversifying investment
Divestment
Financial economics
Foreign direct investment
Gold as an investment
Investor profile
Investor relations
Investment-specific technological progress
Kelly Criterion For Stock Market
Market trends
Megaproject
Over-investing
Philatelic investment
Regulation Fair Disclosure
Rate of return
Saving
Silver as an investment
Speculation
Stock trader
Value investing
List of marketing topics
List of management topics
List of economics topics
List of accounting topics
List of finance topics
List of economists
List of financial services companies (by country)
FINANCIAL FREEDOM
Financial Freedom
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Financial freedom describes a well-planned lifestyle where one no longer is required to work for income to cover their expenses. Contrary to popular belief, it does not require being free of debt, as a debt payment is just another expense. Typically, "Financial Freedom" can be attained in one of two ways (or a combination of the two): 1. Enough passive investment income to cover one's expenses. 2. A large enough "nest egg" that can be liquidated over time to cover one's expenses.
Simply said, financial freedom is one point in life when you do not work for money anymore.
Loosely defined, "financial freedom" is also a marketing catch phrase commonly used by financial planners and popular financial advisors such as Suze Orman, author of The Nine Steps to Financial Freedom (ISBN 0-609-80186-4).
The downside is, the phrase is also often employed in attempts at advance fee fraud. E-mail and snail-mail solicitaions often promise "financial freedom" in return for a couple of hours a week work, or in return for sharing one's bank account information with the widow of the director of Nigeria's central bank, etc.
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Financial freedom describes a well-planned lifestyle where one no longer is required to work for income to cover their expenses. Contrary to popular belief, it does not require being free of debt, as a debt payment is just another expense. Typically, "Financial Freedom" can be attained in one of two ways (or a combination of the two): 1. Enough passive investment income to cover one's expenses. 2. A large enough "nest egg" that can be liquidated over time to cover one's expenses.
Simply said, financial freedom is one point in life when you do not work for money anymore.
Loosely defined, "financial freedom" is also a marketing catch phrase commonly used by financial planners and popular financial advisors such as Suze Orman, author of The Nine Steps to Financial Freedom (ISBN 0-609-80186-4).
The downside is, the phrase is also often employed in attempts at advance fee fraud. E-mail and snail-mail solicitaions often promise "financial freedom" in return for a couple of hours a week work, or in return for sharing one's bank account information with the widow of the director of Nigeria's central bank, etc.
INTERNET TELEPHONY
Internet telephony service provider
From Wikipedia, the free encyclopedia
(Redirected from Internet Telephony Service Provider)
Jump to: navigation, search
An ITSP (Internet Telephony Service Provider) offers an Internet data service for making telephone calls using VoIP (Voice over IP) technology. Most ITSPs use SIP, H.323, or IAX (although H.323 use is declining) for transmitting telephone calls as IP data packets. Customers may use traditional telephones with an analog telephony adapter (ATA) providing RJ11 to Ethernet connection.
In the United States, net2Phone began offering consumer VoIP service in 1995.[citation needed] Before 2003, many VoIP services required customers to make and receive phone calls through a personal computer on a LAN.
ITSP's are also known as VSP (Voice Service Provider) or simply VoIP Providers.
From Wikipedia, the free encyclopedia
(Redirected from Internet Telephony Service Provider)
Jump to: navigation, search
An ITSP (Internet Telephony Service Provider) offers an Internet data service for making telephone calls using VoIP (Voice over IP) technology. Most ITSPs use SIP, H.323, or IAX (although H.323 use is declining) for transmitting telephone calls as IP data packets. Customers may use traditional telephones with an analog telephony adapter (ATA) providing RJ11 to Ethernet connection.
In the United States, net2Phone began offering consumer VoIP service in 1995.[citation needed] Before 2003, many VoIP services required customers to make and receive phone calls through a personal computer on a LAN.
ITSP's are also known as VSP (Voice Service Provider) or simply VoIP Providers.
Search Engine Optimization [SEO ]
Search engine optimization
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Structure of a typical search results pageInternet Marketing
Display advertising
Interactive advertising
Email marketing
Web analytics
Affiliate marketing
Cost Per Action
Revenue sharing
Contextual advertising
Search engine marketing
Search engine optimization
Social media optimization
Pay Per Click advertising
Paid inclusion
This box: view • talk • edit
Search engine optimization (SEO) is the process of improving the volume and quality of traffic to a web site from search engines via "natural" ("organic" or "algorithmic") search results. Usually, the earlier a site is presented in the search results, or the higher it "ranks," the more searchers will visit that site. SEO can also target different kinds of search, including image search, local search, and industry-specific vertical search engines.
As a marketing strategy for increasing a site's relevancy, SEO considers how search algorithms work and what people search for. SEO efforts may involve a site's coding, presentation, and structure, as well as fixing problems that could prevent search engine indexing programs from fully spidering a site. Other, more noticeable efforts may include adding unique content to a site, and making sure that the content is easily indexed by search engines and also appeals to human visitors.
The term SEO can also refer to "search engine optimizers," a term adopted by an industry of consultants who carry out optimization projects on behalf of clients, and by employees who perform SEO services in-house. Search engine optimizers may offer SEO as a stand-alone service or as a part of a broader marketing campaign. Because effective SEO may require changes to the HTML source code of a site, SEO tactics may be incorporated into web site development and design. The term "search engine friendly" may be used to describe web site designs, menus, content management systems and shopping carts that are easy to optimize.
Contents [hide]
1 History
2 Webmasters and search engines
2.1 Getting listings
2.2 Preventing listings
3 White hat versus black hat
4 As a marketing strategy
5 International markets
6 Legal precedents
7 References
8 See also
History
Webmasters and content providers began optimizing sites for search engines in the mid-1990s, as the first search engines were cataloging the early Web. Initially, all a webmaster needed to do was submit a page, or URL, to the various engines which would send a spider to "crawl" that page, extract links to other pages from it, and return information found on the page to be indexed.[1] The process involves a search engine spider downloading a page and storing it on the search engine's own server, where a second program, known as an indexer, extracts various information about the page, such as the words it contains and where these are located, as well as any weight for specific words, as well as any and all links the page contains, which are then placed into a scheduler for crawling at a later date.
Site owners started to recognize the value of having their sites highly ranked and visible in search engine results, creating an opportunity for both white hat and black hat SEO practitioners. According to industry analyst Danny Sullivan, the earliest known use of the phrase "search engine optimization" was a spam message posted on Usenet on July 26, 1997.[2]
Early versions of search algorithms relied on webmaster-provided information such as the keyword meta tag, or index files in engines like ALIWEB. Meta-tags provided a guide to each page's content. But using meta data to index pages was found to be less than reliable, because some webmasters abused meta tags by including irrelevant keywords to artificially increase page impressions for their website and to increase their ad revenue. Cost per thousand impressions was at the time the common means of monetizing content websites. Inaccurate, incomplete, and inconsistent meta data in meta tags caused pages to rank for irrelevant searches, and fail to rank for relevant searches.[3] Web content providers also manipulated a number of attributes within the HTML source of a page in an attempt to rank well in search engines.[4]
By relying so much on factors exclusively within a webmaster's control, early search engines suffered from abuse and ranking manipulation. To provide better results to their users, search engines had to adapt to ensure their results pages showed the most relevant search results, rather than unrelated pages stuffed with numerous keywords by unscrupulous webmasters. Search engines responded by developing more complex ranking algorithms, taking into account additional factors that were more difficult for webmasters to manipulate.
While graduate students at Stanford University, Larry Page and Sergey Brin developed a search engine called "backrub" that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links.[5] PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random surfer.
Page and Brin founded Google in 1998. Google attracted a loyal following among the growing number of Internet users, who liked its simple design.[6] Off-page factors such as PageRank and hyperlink analysis were considered, as well as on-page factors, to enable Google to avoid the kind of manipulation seen in search engines that only considered on-page factors for their rankings. Although PageRank was more difficult to game, webmasters had already developed link building tools and schemes to influence the Inktomi search engine, and these methods proved similarly applicable to gaining PageRank. Many sites focused on exchanging, buying, and selling links, often on a massive scale. Some of these schemes, or link farms, involved the creation of thousands of sites for the sole purpose of link spamming.[7]
To reduce the impact of link schemes, as of 2007, search engines consider a wide range of undisclosed factors for their ranking algorithms. As a search engine may use hundreds of factors in ranking the listings on its SERPs, the factors themselves and the weight each carries can change continually, and algorithms can differ widely. The three leading search engines, Google, Yahoo and Microsoft's Live.com, do not disclose the algorithms they use to rank pages. Notable SEOs, such as Rand Fishkin, Barry Schwartz, Aaron Wall and Jill Whalen, have studied different approaches to search engine optimization, and have published their expert opinions in online forums and blogs.[8][9] SEO practitioners may also study patents held by various search engines to gain insight into the algorithms.[10]
Webmasters and search engines
By 1997 search engines recognized that some webmasters were making efforts to rank well in their search engines, and even manipulating the page rankings in search results. Early search engines, such as Infoseek, adjusted their algorithms to prevent webmasters from manipulating rankings by stuffing pages with excessive or irrelevant keywords.[11]
Due to the high marketing value of targeted search results, there is potential for an adversarial relationship between search engines and SEOs. In 2005, an annual conference, AIRWeb, Adversarial Information Retrieval on the Web,[12] was created to discuss and minimize the damaging effects of aggressive web content providers.
SEO companies that employ overly aggressive techniques can get their client websites banned from the search results. In 2005, the Wall Street Journal profiled a company, Traffic Power, that allegedly used high-risk techniques and failed to disclose those risks to its clients.[13] Wired reported the same company sued a blogger for mentioning that they were banned.[14] Google's Matt Cutts later confirmed that Google did in fact ban Traffic Power and some of its clients.[15]
Some search engines have also reached out to the SEO industry, and are frequent sponsors and guests at SEO conferences and seminars. In fact, with the advent of paid inclusion, some search engines now have a vested interest in the health of the optimization community. Major search engines provide information and guidelines to help with site optimization.[16][17][18] Google has a Sitemaps program[19] to help webmasters learn if Google is having any problems indexing their website and also provides data on Google traffic to the website. Yahoo! Site Explorer provides a way for webmasters to submit URLs, determine how many pages are in the Yahoo! index and view link information.[20]
Getting listings
The leading search engines, Google, Yahoo! and Microsoft, use crawlers to find pages for their algorithmic search results. Pages that are linked from other search engine indexed pages do not need to be submitted because they are found automatically. Some search engines, notably Yahoo!, operate a paid submission service that guarantee crawling for either a set fee or cost per click.[21] Such programs usually guarantee inclusion in the database, but do not guarantee specific ranking within the search results.[22] Yahoo's paid inclusion program has drawn criticism from advertisers and competitors.[23] Two major directories, the Yahoo Directory and the Open Directory Project both require manual submission and human editorial review.[24] Google offers Google Sitemaps, for which an XML type feed can be created and submitted for free to ensure that all pages are found, especially pages that aren't discoverable by automatically following links.[25]
Search engine crawlers may look at a number of different factors when crawling a site. Not every page is indexed by the search engines. Distance of pages from the root directory of a site may also be a factor in whether or not pages get crawled.[26]
Preventing listings
Main article: robots.txt
To avoid undesirable search listings, webmasters can instruct spiders not to crawl certain files or directories through the standard robots.txt file in the root directory of the domain. Additionally, a page can be explicitly excluded from a search engine's database by using a meta tag specific to robots. When a search engine visits a site, the robots.txt located in the root directory is the first file crawled. The robots.txt file is then parsed, and will instruct the robot as to which pages are not to be crawled. As a search engine crawler may keep a cached copy of this file, it may on occasion crawl pages a webmaster does not wish crawled. Pages typically prevented from being crawled include login specific pages such as shopping carts and user-specific content such as search results from internal searches. In March 2007, Google warned webmasters that they should prevent indexing of internal search results because those pages are considered search spam.[27]
White hat versus black hat
SEO techniques are classified by some into two broad categories: techniques that search engines recommend as part of good design, and those techniques that search engines do not approve of and attempt to minimize the effect of, referred to as spamdexing. Some industry commentators classify these methods, and the practitioners who utilize them, as either white hat SEO, or black hat SEO.[28] Different hat colors do not necessarily imply differences in ethics as much as differences in business models. White hats tend to produce results that last a long time, whereas black hats anticipate that their sites will eventually be banned once the search engines discover what they are doing.[29]
An SEO tactic, technique or method is considered white hat if it conforms to the search engines' guidelines and involves no deception. As the search engine guidelines[30][16][17][18] are not written as a series of rules or commandments, this is an important distinction to note. White hat SEO is not just about following guidelines, but is about ensuring that the content a search engine indexes and subsequently ranks is the same content a user will see.
White hat advice is generally summed up as creating content for users, not for search engines, and then making that content easily accessible to the spiders, rather than attempting to game the algorithm. White hat SEO is in many ways similar to web development that promotes accessibility,[31] although the two are not identical.
Black hat SEO attempts to improve rankings in ways that are disapproved of by the search engines, or involve deception. One black hat technique uses text that is hidden, either as text colored similar to the background, in an invisible div, or positioned off screen. Another method redirects users from a page that is built for search engines to one that is more human friendly. A method that sends a user to a page that was different from the page the search engined ranked is black hat as a rule. The black hat practice of serving one version of a page to search engine spiders and another version to human visitors is called cloaking.
Search engines may penalize sites they discover using black hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review.
One infamous example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[32] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's list.[33]
As a marketing strategy
Eye tracking studies have shown that searchers scan a search results page from top to bottom and left to right, looking for a relevant result. Placement at or near the top of the rankings therefore increases the number of searchers who will visit a site.[34] However, more search engine referrals does not guarantee more sales. SEO is not necessarily an appropriate strategy for every website, and other Internet marketing strategies can be much more effective, depending on the site operator's goals.[35]A successful Internet marketing campaign may drive organic search results to pages, but it also may involve the use of paid advertising on search engines and other pages, building high quality web pages to engage and persuade, addressing technical issues that may keep search engines from crawling and indexing those sites, setting up analytics programs to enable site owners to measure their successes, and improving a site's conversion rate.[36]
SEO may generate a return on investment. However, search engines are not paid for organic search traffic, their algorithms change, and there are no guarantees of continued referrals. Due to this lack of guarantees and certainty, a business that relies heavily on search engine traffic can suffer major losses if the search engines stop sending visitors.[37] According to notable technologist Jakob Nielsen, website operators should liberate themselves from dependence on search engine traffic.[38] A top ranked SEO blog Seomoz.org[39] has reported, "Search marketers, in a twist of irony, receive a very small share of their traffic from search engines." Instead, their main sources of traffic are links from other websites. [40]
International markets
A Baidu search results pageThe search engines' market shares vary from market to market, as does competition. In 2003, Danny Sullivan stated that Google represented about 75% of all searches.[41] In markets outside the United States, Google's share is often larger, and Google remains the dominant search engine worldwide as of 2007.[42] As of 2006, Google held about 40% of the market in the United States, but Google had an 85-90% market share in Germany.[43] While there were hundreds of SEO firms in the US at that time, there were only about five in Germany.[43]
In Russia the situation is reversed. Local search engine Yandex controls 50% of the paid advertising revenue, while Google has less than 9%.[44] In China, Baidu continues to lead in market share, although Google has been gaining share as of 2007.[45]
Successful search optimization for international markets may require professional translation of web pages, registration of a domain name with a top level domain in the target market, and web hosting that provides a local IP address. Otherwise, the fundamental elements of search optimization are essentially the same, regardless of language.[43]
Legal precedents
In 2002, SearchKing filed suit in an Oklahoma court against the search engine Google. SearchKing's claim was that Google's tactics to prevent spamdexing constituted an unfair business practice. In May 2003, the court pronounced a summary judgment in Google's favor. [46]
In March 2006, KinderStart.com, LLC filed a First Amendment complaint against Google and also attempted to include potential members of the class of plaintiffs in a class action.[47] The plaintiff's web site was removed from Google's index prior to the lawsuit and the amount of traffic to the site plummeted. On March 16, 2007 the United States District Court dismissed KinderStart's complaint without leave to amend, and partially granted Google's motion for Rule 11 sanctions against KinderStart's attorney, requiring him to pay part of Google's legal expenses.[48][49
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Structure of a typical search results pageInternet Marketing
Display advertising
Interactive advertising
Email marketing
Web analytics
Affiliate marketing
Cost Per Action
Revenue sharing
Contextual advertising
Search engine marketing
Search engine optimization
Social media optimization
Pay Per Click advertising
Paid inclusion
This box: view • talk • edit
Search engine optimization (SEO) is the process of improving the volume and quality of traffic to a web site from search engines via "natural" ("organic" or "algorithmic") search results. Usually, the earlier a site is presented in the search results, or the higher it "ranks," the more searchers will visit that site. SEO can also target different kinds of search, including image search, local search, and industry-specific vertical search engines.
As a marketing strategy for increasing a site's relevancy, SEO considers how search algorithms work and what people search for. SEO efforts may involve a site's coding, presentation, and structure, as well as fixing problems that could prevent search engine indexing programs from fully spidering a site. Other, more noticeable efforts may include adding unique content to a site, and making sure that the content is easily indexed by search engines and also appeals to human visitors.
The term SEO can also refer to "search engine optimizers," a term adopted by an industry of consultants who carry out optimization projects on behalf of clients, and by employees who perform SEO services in-house. Search engine optimizers may offer SEO as a stand-alone service or as a part of a broader marketing campaign. Because effective SEO may require changes to the HTML source code of a site, SEO tactics may be incorporated into web site development and design. The term "search engine friendly" may be used to describe web site designs, menus, content management systems and shopping carts that are easy to optimize.
Contents [hide]
1 History
2 Webmasters and search engines
2.1 Getting listings
2.2 Preventing listings
3 White hat versus black hat
4 As a marketing strategy
5 International markets
6 Legal precedents
7 References
8 See also
History
Webmasters and content providers began optimizing sites for search engines in the mid-1990s, as the first search engines were cataloging the early Web. Initially, all a webmaster needed to do was submit a page, or URL, to the various engines which would send a spider to "crawl" that page, extract links to other pages from it, and return information found on the page to be indexed.[1] The process involves a search engine spider downloading a page and storing it on the search engine's own server, where a second program, known as an indexer, extracts various information about the page, such as the words it contains and where these are located, as well as any weight for specific words, as well as any and all links the page contains, which are then placed into a scheduler for crawling at a later date.
Site owners started to recognize the value of having their sites highly ranked and visible in search engine results, creating an opportunity for both white hat and black hat SEO practitioners. According to industry analyst Danny Sullivan, the earliest known use of the phrase "search engine optimization" was a spam message posted on Usenet on July 26, 1997.[2]
Early versions of search algorithms relied on webmaster-provided information such as the keyword meta tag, or index files in engines like ALIWEB. Meta-tags provided a guide to each page's content. But using meta data to index pages was found to be less than reliable, because some webmasters abused meta tags by including irrelevant keywords to artificially increase page impressions for their website and to increase their ad revenue. Cost per thousand impressions was at the time the common means of monetizing content websites. Inaccurate, incomplete, and inconsistent meta data in meta tags caused pages to rank for irrelevant searches, and fail to rank for relevant searches.[3] Web content providers also manipulated a number of attributes within the HTML source of a page in an attempt to rank well in search engines.[4]
By relying so much on factors exclusively within a webmaster's control, early search engines suffered from abuse and ranking manipulation. To provide better results to their users, search engines had to adapt to ensure their results pages showed the most relevant search results, rather than unrelated pages stuffed with numerous keywords by unscrupulous webmasters. Search engines responded by developing more complex ranking algorithms, taking into account additional factors that were more difficult for webmasters to manipulate.
While graduate students at Stanford University, Larry Page and Sergey Brin developed a search engine called "backrub" that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links.[5] PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random surfer.
Page and Brin founded Google in 1998. Google attracted a loyal following among the growing number of Internet users, who liked its simple design.[6] Off-page factors such as PageRank and hyperlink analysis were considered, as well as on-page factors, to enable Google to avoid the kind of manipulation seen in search engines that only considered on-page factors for their rankings. Although PageRank was more difficult to game, webmasters had already developed link building tools and schemes to influence the Inktomi search engine, and these methods proved similarly applicable to gaining PageRank. Many sites focused on exchanging, buying, and selling links, often on a massive scale. Some of these schemes, or link farms, involved the creation of thousands of sites for the sole purpose of link spamming.[7]
To reduce the impact of link schemes, as of 2007, search engines consider a wide range of undisclosed factors for their ranking algorithms. As a search engine may use hundreds of factors in ranking the listings on its SERPs, the factors themselves and the weight each carries can change continually, and algorithms can differ widely. The three leading search engines, Google, Yahoo and Microsoft's Live.com, do not disclose the algorithms they use to rank pages. Notable SEOs, such as Rand Fishkin, Barry Schwartz, Aaron Wall and Jill Whalen, have studied different approaches to search engine optimization, and have published their expert opinions in online forums and blogs.[8][9] SEO practitioners may also study patents held by various search engines to gain insight into the algorithms.[10]
Webmasters and search engines
By 1997 search engines recognized that some webmasters were making efforts to rank well in their search engines, and even manipulating the page rankings in search results. Early search engines, such as Infoseek, adjusted their algorithms to prevent webmasters from manipulating rankings by stuffing pages with excessive or irrelevant keywords.[11]
Due to the high marketing value of targeted search results, there is potential for an adversarial relationship between search engines and SEOs. In 2005, an annual conference, AIRWeb, Adversarial Information Retrieval on the Web,[12] was created to discuss and minimize the damaging effects of aggressive web content providers.
SEO companies that employ overly aggressive techniques can get their client websites banned from the search results. In 2005, the Wall Street Journal profiled a company, Traffic Power, that allegedly used high-risk techniques and failed to disclose those risks to its clients.[13] Wired reported the same company sued a blogger for mentioning that they were banned.[14] Google's Matt Cutts later confirmed that Google did in fact ban Traffic Power and some of its clients.[15]
Some search engines have also reached out to the SEO industry, and are frequent sponsors and guests at SEO conferences and seminars. In fact, with the advent of paid inclusion, some search engines now have a vested interest in the health of the optimization community. Major search engines provide information and guidelines to help with site optimization.[16][17][18] Google has a Sitemaps program[19] to help webmasters learn if Google is having any problems indexing their website and also provides data on Google traffic to the website. Yahoo! Site Explorer provides a way for webmasters to submit URLs, determine how many pages are in the Yahoo! index and view link information.[20]
Getting listings
The leading search engines, Google, Yahoo! and Microsoft, use crawlers to find pages for their algorithmic search results. Pages that are linked from other search engine indexed pages do not need to be submitted because they are found automatically. Some search engines, notably Yahoo!, operate a paid submission service that guarantee crawling for either a set fee or cost per click.[21] Such programs usually guarantee inclusion in the database, but do not guarantee specific ranking within the search results.[22] Yahoo's paid inclusion program has drawn criticism from advertisers and competitors.[23] Two major directories, the Yahoo Directory and the Open Directory Project both require manual submission and human editorial review.[24] Google offers Google Sitemaps, for which an XML type feed can be created and submitted for free to ensure that all pages are found, especially pages that aren't discoverable by automatically following links.[25]
Search engine crawlers may look at a number of different factors when crawling a site. Not every page is indexed by the search engines. Distance of pages from the root directory of a site may also be a factor in whether or not pages get crawled.[26]
Preventing listings
Main article: robots.txt
To avoid undesirable search listings, webmasters can instruct spiders not to crawl certain files or directories through the standard robots.txt file in the root directory of the domain. Additionally, a page can be explicitly excluded from a search engine's database by using a meta tag specific to robots. When a search engine visits a site, the robots.txt located in the root directory is the first file crawled. The robots.txt file is then parsed, and will instruct the robot as to which pages are not to be crawled. As a search engine crawler may keep a cached copy of this file, it may on occasion crawl pages a webmaster does not wish crawled. Pages typically prevented from being crawled include login specific pages such as shopping carts and user-specific content such as search results from internal searches. In March 2007, Google warned webmasters that they should prevent indexing of internal search results because those pages are considered search spam.[27]
White hat versus black hat
SEO techniques are classified by some into two broad categories: techniques that search engines recommend as part of good design, and those techniques that search engines do not approve of and attempt to minimize the effect of, referred to as spamdexing. Some industry commentators classify these methods, and the practitioners who utilize them, as either white hat SEO, or black hat SEO.[28] Different hat colors do not necessarily imply differences in ethics as much as differences in business models. White hats tend to produce results that last a long time, whereas black hats anticipate that their sites will eventually be banned once the search engines discover what they are doing.[29]
An SEO tactic, technique or method is considered white hat if it conforms to the search engines' guidelines and involves no deception. As the search engine guidelines[30][16][17][18] are not written as a series of rules or commandments, this is an important distinction to note. White hat SEO is not just about following guidelines, but is about ensuring that the content a search engine indexes and subsequently ranks is the same content a user will see.
White hat advice is generally summed up as creating content for users, not for search engines, and then making that content easily accessible to the spiders, rather than attempting to game the algorithm. White hat SEO is in many ways similar to web development that promotes accessibility,[31] although the two are not identical.
Black hat SEO attempts to improve rankings in ways that are disapproved of by the search engines, or involve deception. One black hat technique uses text that is hidden, either as text colored similar to the background, in an invisible div, or positioned off screen. Another method redirects users from a page that is built for search engines to one that is more human friendly. A method that sends a user to a page that was different from the page the search engined ranked is black hat as a rule. The black hat practice of serving one version of a page to search engine spiders and another version to human visitors is called cloaking.
Search engines may penalize sites they discover using black hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review.
One infamous example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[32] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's list.[33]
As a marketing strategy
Eye tracking studies have shown that searchers scan a search results page from top to bottom and left to right, looking for a relevant result. Placement at or near the top of the rankings therefore increases the number of searchers who will visit a site.[34] However, more search engine referrals does not guarantee more sales. SEO is not necessarily an appropriate strategy for every website, and other Internet marketing strategies can be much more effective, depending on the site operator's goals.[35]A successful Internet marketing campaign may drive organic search results to pages, but it also may involve the use of paid advertising on search engines and other pages, building high quality web pages to engage and persuade, addressing technical issues that may keep search engines from crawling and indexing those sites, setting up analytics programs to enable site owners to measure their successes, and improving a site's conversion rate.[36]
SEO may generate a return on investment. However, search engines are not paid for organic search traffic, their algorithms change, and there are no guarantees of continued referrals. Due to this lack of guarantees and certainty, a business that relies heavily on search engine traffic can suffer major losses if the search engines stop sending visitors.[37] According to notable technologist Jakob Nielsen, website operators should liberate themselves from dependence on search engine traffic.[38] A top ranked SEO blog Seomoz.org[39] has reported, "Search marketers, in a twist of irony, receive a very small share of their traffic from search engines." Instead, their main sources of traffic are links from other websites. [40]
International markets
A Baidu search results pageThe search engines' market shares vary from market to market, as does competition. In 2003, Danny Sullivan stated that Google represented about 75% of all searches.[41] In markets outside the United States, Google's share is often larger, and Google remains the dominant search engine worldwide as of 2007.[42] As of 2006, Google held about 40% of the market in the United States, but Google had an 85-90% market share in Germany.[43] While there were hundreds of SEO firms in the US at that time, there were only about five in Germany.[43]
In Russia the situation is reversed. Local search engine Yandex controls 50% of the paid advertising revenue, while Google has less than 9%.[44] In China, Baidu continues to lead in market share, although Google has been gaining share as of 2007.[45]
Successful search optimization for international markets may require professional translation of web pages, registration of a domain name with a top level domain in the target market, and web hosting that provides a local IP address. Otherwise, the fundamental elements of search optimization are essentially the same, regardless of language.[43]
Legal precedents
In 2002, SearchKing filed suit in an Oklahoma court against the search engine Google. SearchKing's claim was that Google's tactics to prevent spamdexing constituted an unfair business practice. In May 2003, the court pronounced a summary judgment in Google's favor. [46]
In March 2006, KinderStart.com, LLC filed a First Amendment complaint against Google and also attempted to include potential members of the class of plaintiffs in a class action.[47] The plaintiff's web site was removed from Google's index prior to the lawsuit and the amount of traffic to the site plummeted. On March 16, 2007 the United States District Court dismissed KinderStart's complaint without leave to amend, and partially granted Google's motion for Rule 11 sanctions against KinderStart's attorney, requiring him to pay part of Google's legal expenses.[48][49
CARDIOLOGY TREATMENT
Interventional cardiology
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Jump to: navigation, search
Interventional cardiology is a branch of the medical specialty of cardiology that deals specifically with the catheter based treatment of structural heart diseases.
A large number of procedures can be performed on the heart by catheterization. This most commonly involves the insertion of a sheath into the femoral artery (but, in practice, any large peripheral artery or vein) and cannulating the heart under X-ray visualization (most commonly fluoroscopy, a real-time x-ray).
Procedures performed by specialists in interventional cardiology:
Angioplasty (PTCA, Percutaneous Transluminal Coronary Angioplasty) - for coronary atherosclerosis
Valvuloplasty - dilation of narrowed cardiac valves (usually mitral, aortic or pulmonary)
Procedures for congenital heart disease - insertion of occluders for ventricular or atrial septal defects, occlusion of patent ductus arteriosus, angioplasty of great vessels
Emergency angioplasty and stenting of occluded coronary vessels in the setting of acute myocardial infarction
Invasive procedures of the heart to treat arrhythmias are performed by specialists in clinical cardiac electrophysiology
Surgery of the heart is done by the specialty of cardiothoracic surgery. Some interventional cardiology procedures are only performed when there is cardiothoracic surgery expertise in the hospital, in case of complications.
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Interventional cardiology is a branch of the medical specialty of cardiology that deals specifically with the catheter based treatment of structural heart diseases.
A large number of procedures can be performed on the heart by catheterization. This most commonly involves the insertion of a sheath into the femoral artery (but, in practice, any large peripheral artery or vein) and cannulating the heart under X-ray visualization (most commonly fluoroscopy, a real-time x-ray).
Procedures performed by specialists in interventional cardiology:
Angioplasty (PTCA, Percutaneous Transluminal Coronary Angioplasty) - for coronary atherosclerosis
Valvuloplasty - dilation of narrowed cardiac valves (usually mitral, aortic or pulmonary)
Procedures for congenital heart disease - insertion of occluders for ventricular or atrial septal defects, occlusion of patent ductus arteriosus, angioplasty of great vessels
Emergency angioplasty and stenting of occluded coronary vessels in the setting of acute myocardial infarction
Invasive procedures of the heart to treat arrhythmias are performed by specialists in clinical cardiac electrophysiology
Surgery of the heart is done by the specialty of cardiothoracic surgery. Some interventional cardiology procedures are only performed when there is cardiothoracic surgery expertise in the hospital, in case of complications.
WOMEN FITNESS
PROPER DIET AND EXERCISE IS THE ONLY ROAD GAINING MUSCLE AND/OR LOSING FAT - THERE ARE NO SHORT-CUTS (EXCEPT FOR DANGEROUS AND ILLEGAL DRUGS)! NO "MIRACLE" EXERCISE DEVICE OR SUPPLEMENT CAN BUILD MUSCLE OR BURN FAT, AS THE KEY TO TRANSFORMING A SKINNY, OVERWEIGHT, OR AVERAGE BODY IS PROPER DIET/EXERCISE TECHNIQUES.
That's the message, Women Fitness team carries to women all over the world. Our team comprising of fitness trainers, nutritionists, gynecologists and orthopedic surgeon aim to bring you a complete resource on how to achieve a healthy and permanent weight loss. The "Women Fitness Weight loss Center" program consists of diet, exercise, and behavioral modification. WF team of health & fitness experts successfully use the Weight loss program to help women lose weight and monitor their progress. One or more WF counselors will be at your service to answer your query's at an individual basis. However it important that you keep in mind that our staff does not offer medical counseling. Please feel free to ask for more details about our program.
The body is composed of fat and fat-free components, such as muscle, bone, and water. Each component plays a critical role in the health of the body. Fat Mass (FM) is the total amount of fat in the body. The ideal amount of fat for minimal disease risk is 23%-31% of total body weight in women.
Fat mass consists of the following types of fat:
Subcutaneous Fat, also called Subcutaneous Adipose Tissue (SAT), is located directly beneath the skin. Subcutaneous fat serves as insulation against outside cold.
Visceral Fat, also called Visceral Adipose Tissue (VAT), is located deeper within the body. Visceral fat serves as a cushion between organs. Omental and mesenteric fat (in the abdomen) are examples of visceral fat.
Fat-Free Mass (FFM), also called Lean Body Mass (LBM), is the total amount of nonfat (lean) parts of the body. It consists of approximately 73% water, 20% protein, 6% minerals, and 1% ash.
source : www.womenfitness.net
That's the message, Women Fitness team carries to women all over the world. Our team comprising of fitness trainers, nutritionists, gynecologists and orthopedic surgeon aim to bring you a complete resource on how to achieve a healthy and permanent weight loss. The "Women Fitness Weight loss Center" program consists of diet, exercise, and behavioral modification. WF team of health & fitness experts successfully use the Weight loss program to help women lose weight and monitor their progress. One or more WF counselors will be at your service to answer your query's at an individual basis. However it important that you keep in mind that our staff does not offer medical counseling. Please feel free to ask for more details about our program.
The body is composed of fat and fat-free components, such as muscle, bone, and water. Each component plays a critical role in the health of the body. Fat Mass (FM) is the total amount of fat in the body. The ideal amount of fat for minimal disease risk is 23%-31% of total body weight in women.
Fat mass consists of the following types of fat:
Subcutaneous Fat, also called Subcutaneous Adipose Tissue (SAT), is located directly beneath the skin. Subcutaneous fat serves as insulation against outside cold.
Visceral Fat, also called Visceral Adipose Tissue (VAT), is located deeper within the body. Visceral fat serves as a cushion between organs. Omental and mesenteric fat (in the abdomen) are examples of visceral fat.
Fat-Free Mass (FFM), also called Lean Body Mass (LBM), is the total amount of nonfat (lean) parts of the body. It consists of approximately 73% water, 20% protein, 6% minerals, and 1% ash.
source : www.womenfitness.net
SECURED ONLINE TRANSACTION
Online transaction processing
From Wikipedia, the free encyclopedia
(Redirected from Online Transaction Processing)
Jump to: navigation, search
Online Transaction Processing (or OLTP) is a class of programs that facilitate and manage transaction-oriented applications, typically for data entry and retrieval transaction processing.
The term Online Transaction Processing is somewhat ambiguous: some understand "transaction" as a reference to computer or database transactions, while others (such as the Transaction Processing Performance Council) define it in terms of business or commercial transactions.
OLTP also refers to computer processing in which the computer responds immediately to user requests. An automatic teller machine (ATM) for a bank is an example of transaction processing.
Contents [hide]
1 Uses
2 Requirements
3 Benefits
4 Disadvantages
5 See also
6 External links
[edit] Uses
It is a technique used in a number of industries, including banking, airlines, mailorder, supermarkets, and manufacturers. Some applications of OLTP include electronic banking, order processing, employee time clock systems, e-commerce, and eTrading.
Probably the most widely installed OLTP product is IBM's CICS (Customer Information Control System).[citation needed]
[edit] Requirements
Today's online transaction processing increasingly requires support for transactions that span a network and may include more than one company. For this reason, new OLTP software uses client/server processing and brokering software that allows transactions to run on different computer platforms in a network.
In large applications, efficient OLTP may depend on sophisticated transaction management software (such as CICS) and/or database optimization tactics to facilitate the processing of large numbers of concurrent updates to an OLTP-oriented database.
For even more demanding decentralized database systems, OLTP brokering programs can distribute transaction processing among multiple computers on a network. OLTP is often integrated into service-oriented architecture and Web services.
[edit] Benefits
Online Transaction Processing has two key benefits: simplicity and efficiency.
Reduced paper trails and the faster, more accurate forecasts for revenues and expenses are both examples of how OLTP makes things simpler for businesses. It also provides a concrete foundation for a stable organization because of the timely updating. Another simplicity factor is that of allowing consumers the choice of how they want to pay, making it that much more enticing to make transactions.
OLTP is proven efficient because it vastly broadens the consumer base for an organization, the individual processes are faster, and it’s available 24/7.
[edit] Disadvantages
It is a great tool for any organization, but in using OLTP, there are a few things to be wary of: the security issues and economic costs.
One of the benefits of OLTP is also an attribute to a potential problem. The worldwide availability that this system provides to companies makes their databases that much more susceptible to intruders and hackers.
For B2B transactions, businesses must go offline to complete certain steps of an individual process, causing buyers and suppliers to miss out on some of the efficiency benefits that the system provides. As simple as OLTP is, the simplest disruption in the system has the potential to cause a great deal of problems, causing a waste of both time and money. Another economic cost is the potential for server failures. This can cause delays or even wipe out an immeasurable amount of data.
[edit] See also
Data mart
Data warehouse
OLAP
ETL
Transaction processing
Database transaction
Derby in-memory Java Database
IBM Customer Information Control System
From Wikipedia, the free encyclopedia
(Redirected from Online Transaction Processing)
Jump to: navigation, search
Online Transaction Processing (or OLTP) is a class of programs that facilitate and manage transaction-oriented applications, typically for data entry and retrieval transaction processing.
The term Online Transaction Processing is somewhat ambiguous: some understand "transaction" as a reference to computer or database transactions, while others (such as the Transaction Processing Performance Council) define it in terms of business or commercial transactions.
OLTP also refers to computer processing in which the computer responds immediately to user requests. An automatic teller machine (ATM) for a bank is an example of transaction processing.
Contents [hide]
1 Uses
2 Requirements
3 Benefits
4 Disadvantages
5 See also
6 External links
[edit] Uses
It is a technique used in a number of industries, including banking, airlines, mailorder, supermarkets, and manufacturers. Some applications of OLTP include electronic banking, order processing, employee time clock systems, e-commerce, and eTrading.
Probably the most widely installed OLTP product is IBM's CICS (Customer Information Control System).[citation needed]
[edit] Requirements
Today's online transaction processing increasingly requires support for transactions that span a network and may include more than one company. For this reason, new OLTP software uses client/server processing and brokering software that allows transactions to run on different computer platforms in a network.
In large applications, efficient OLTP may depend on sophisticated transaction management software (such as CICS) and/or database optimization tactics to facilitate the processing of large numbers of concurrent updates to an OLTP-oriented database.
For even more demanding decentralized database systems, OLTP brokering programs can distribute transaction processing among multiple computers on a network. OLTP is often integrated into service-oriented architecture and Web services.
[edit] Benefits
Online Transaction Processing has two key benefits: simplicity and efficiency.
Reduced paper trails and the faster, more accurate forecasts for revenues and expenses are both examples of how OLTP makes things simpler for businesses. It also provides a concrete foundation for a stable organization because of the timely updating. Another simplicity factor is that of allowing consumers the choice of how they want to pay, making it that much more enticing to make transactions.
OLTP is proven efficient because it vastly broadens the consumer base for an organization, the individual processes are faster, and it’s available 24/7.
[edit] Disadvantages
It is a great tool for any organization, but in using OLTP, there are a few things to be wary of: the security issues and economic costs.
One of the benefits of OLTP is also an attribute to a potential problem. The worldwide availability that this system provides to companies makes their databases that much more susceptible to intruders and hackers.
For B2B transactions, businesses must go offline to complete certain steps of an individual process, causing buyers and suppliers to miss out on some of the efficiency benefits that the system provides. As simple as OLTP is, the simplest disruption in the system has the potential to cause a great deal of problems, causing a waste of both time and money. Another economic cost is the potential for server failures. This can cause delays or even wipe out an immeasurable amount of data.
[edit] See also
Data mart
Data warehouse
OLAP
ETL
Transaction processing
Database transaction
Derby in-memory Java Database
IBM Customer Information Control System
PREMATURE EJACULATION
Premature ejaculation
From Wikipedia, the free encyclopedia
(Redirected from Premature Ejaculation)
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It has been suggested that Drugs specifically targeted to treat premature ejaculation be merged into this article or section. (Discuss) This article may require cleanup to meet Wikipedia's quality standards.
Please discuss this issue on the talk page or replace this tag with a more specific message.
This article has been tagged since May 2007.
Premature ejaculation (PE), also known as rapid ejaculation, premature climax, early ejaculation, or by the Latin term ejaculatio praecox, is the most common sexual problem in men, affecting 25%-40% of men. It is characterized by a lack of voluntary control over ejaculation. Masters and Johnson stated that a man suffers from premature ejaculation if he ejaculates before his partner achieves orgasm in more than fifty percent of his sexual encounters. Other sex researchers have defined premature ejaculation as occurring if the man ejaculates within two minutes or less of penetration; however, a survey by Alfred Kinsey in the 1950s demonstrated that three quarters of men ejaculated within two minutes of penetration in over half of their sexual encounters. Today, most sex therapists understand premature ejaculation as occurring when a lack of ejaculatory control interferes with sexual or emotional well-being in one or both partners.
Most men experience premature ejaculation at least once in their lives. Often adolescents and young men experience "premature" ejaculation during their first sexual encounters, but eventually learn ejaculatory control. Because there is great variability in both how long it takes men to ejaculate and how long both partners want sex to last, researchers have begun to form a quantitative definition of premature ejaculation. Current evidence supports a median average ejaculation latency time (IELT) of six and a half minutes in 18-30 year olds.[1] If the disorder is defined as an IELT percentile below 2.5, then premature ejaculation could be suggested by an IELT of less than about one and a half minutes. Nevertheless, it is well accepted that men with IELTs below 1.5 minutes could be "happy" with their performance and do not report a lack of control and therefore do not suffer from PE. On the other hand, a man with 2 minutes IELT could present with perception of poor control over his ejaculation, distressed about his condition, has interpersonal difficulties and therefore be diagnosed with PE.
Scientists have long suspected a genetic link to certain forms of premature ejaculation. In one study, ninety-one percent of men who suffered from lifelong premature ejaculation also had a first-relative with lifelong premature ejaculation. Other researchers have noted that men who suffer from premature ejaculation have a faster neurological response in the pelvic muscles. Simple exercises commonly suggested by sex therapists can significantly improve ejaculatory control for men with premature ejaculation caused by neurological factors[citation needed]. Often, these men may benefit from anti-anxiety medication or selective serotonin reuptake inhibitors (SSRIs), such as sertraline or paroxetine. Some men prefer using anaesthetic creams; however, these creams may also deaden sensations in the man's partner, and are not generally recommended by sex therapists.
Psychological factors also commonly contribute to premature ejaculation. While men sometimes underestimate the relationship between sexual performance and emotional well-being, premature ejaculation can be caused by temporary depression, stress over financial matters, unrealistic expectations about performance, a history of sexual repression, or an overall lack of confidence. Interpersonal dynamics strongly contribute to sexual function, and premature ejaculation can be caused by a lack of communication between partners, hurt feelings, or unresolved conflicts that interfere with the ability to achieve emotional intimacy. Neurological premature ejaculation can also lead to other forms of sexual dysfunction, or intensify the existing problem, by creating performance anxiety. In a less pathological context, premature ejaculation could also be simply caused by extreme arousal.
Some physical illnesses, such as a prostate infection, are also known to induce premature ejaculation. In other instances, premature ejaculation is caused by a physical injury that affects the nervous system. Certain medications, such as cold medications containing pseudoephedrine, also cause premature ejaculation. Sexual dysfunction is a common symptom of psychiatric afflictions ranging from bipolar disorder to post-traumatic stress disorder. In these cases, it is best to discuss the issues openly with a physician.
Today it is believed that the neurotransmitor serotonin (5HT) has a central role in modulating ejaculation. Several animal studies have demostrated its inhibitory effect on ejaculation modulated through the PGI system in the brain. Therefore, it is perceived that low level of serotonin in the synaptic cleft in these specific areas in the brain could cause premature ejaculation. This theory is further supported by the proven effectiveness of SSRIs, which increase serotonin level in the synapse, in treating PE.
Contents [hide]
1 Science of Mechanism of Ejaculation
2 Treatment
2.1 Alternative therapies
3 Diagnosis
3.1 Differential diagnosis
3.2 Associated conditions
4 See also
5 References
6 External Links
[edit] Science of Mechanism of Ejaculation
The process of ejaculation requires two sequentially distinct actions, emission and expulsion.
Mechanism of EjaculationThe emission phase is the first one to happen and it involves deposition of semenal fluid from ampullary vasa deferens, seminal vesicles & prostate gland into posterior urethra (Bohlen, et al., 2000). Second phase is the expulsion of semen which involves closure of bladder neck followed by the rhythmic contractions of urethra by pelvic-perineal and bulbospongiosus muscle and intermittent relaxation of external Sphincter urethrae (Master and Turek, 2001).
Sympathetic motor neurons control the emission phase of ejaculation reflex and expulsion phase is executed by somatic and autonomic motor neurons. These motor neurons are located in the thoracolumbar and lumbosacral spinal cord and are activated in a coordinated manner when sufficient sensory input to reach the ejaculatory threshold has entered the central nervous system (De Groat and Booth 1980; Truitt and Coolen 2002). Several areas in the brain, and especially the nucleus paragigantocellularis has been identified to be involved in ejaculatory control (Coolen, et al., 2004).
[edit] Treatment
This section contains instructions, advice, or “how-to” content.
The purpose of Wikipedia is to present facts, not to teach subject matter.
Please help improve this article by removing or rewriting the how-to content, which may qualify for a move to Wikibooks.
Depending on severity, premature ejaculation symptoms can be significantly reduced. In mundane cases, treatments are focused on gradually training and improving mental habituation to sex and physical development of stimulation control. In clinical cases, various medications are being trialled to help slow down the speed of the arousal response.
SSRI antidepressants have been shown to delay ejaculation in men treated for different psychiatry disorders. SSRIs are considered the most effective treatment currently available for PE. These include paroxetine, fluoxetine, sertraline and more. The use of these drugs, that require chronic therapy is limited by the neuropsychiatric side effects. New SSRI drugs specifically targeted to treat premature ejaculation (e.g. dapoxetine) can be taken on an as needed basis and have been recently shown positive results in large phase III studies. Nevertheless dapoxetine is not yet approved by any regulatory authority around the world. There is speculation that some of the associated effects are caused by lowered libido and blood pressure as well as lowered anxiety levels. Other pharmaceutical products known to delay male orgasm are; opioids, cocaine, and diphenhydramine.
The effects of hyperforin extract of Hypericum perforatum, has been evaluated on the ejaculatory reflex duration by using the intravaginal ejaculatory latency time (IELT) and sexual satisfaction (Cannon-Smith and Kaufman, 2007). In this trial sixteen men who desired longer sexual intercourse and without erectile dysfunction took with hypferforin immediately prior to sexual activity. All 16 participants completed the trial and there was a significant increase in mean ejaculation times from 246±29 to 331±34 seconds (p<0.002) in persons taking the hyperforin extract Prolasta. The increase was seen in both the men who reported PE as bothersome and those who did not feel that PE was a problem for them. The effect of Prolasta may be similar to that of dapoxetine.
Local anesthetic creams (like lidocaine, prilocaine and combinations) have shown to be very effective in clinical trials and are being used of the treatment of PE. Their use is limited by its own anesthetic effect that reduce sensation on the penis and vagina.
Most sex therapists prescribe a series of exercises to enable the man to gain ejaculatory control. While the exercises are intended for men who suffer from premature ejaculation, other men can use the exercises to enhance their sex lives. By far the most common exercise is the so-called start-stop technique. While the technique varies, the purpose is to get the male accustomed to maintaining an erection for an extended period of time while gradually increasing sexual tolerance. In doing this exercise, the male obtains an erection through self-stimulation, or masturbation. After achieving an erection, he stops stimulating himself until he begins to lose his erection; at that point, he begins to stimulate himself again. Gradually, over a period of several weeks, he is able to stimulate himself for longer periods of time, eventually gaining ejaculatory control. In order for this technique to be successful, the male should avoid feeling discouraged if he ejaculates rapidly; instead, he should use his sexual responses to learn how to vary the technique in a way that most benefits him. The male can choose to integrate his partner into these exercises.
The male's partner is usually integrated into the exercises. They can stimulate the partner using the stop-start technique. When the male has achieved some level of ejaculatory control, he can insert his penis into his partner without thrusting. After his penis becomes accustomed to being inside his partner, thrusting can be gradually included, according to the male's abilities, using the stop-start technique. In less severe cases, the male might overcome his premature ejaculation early on, making exercises with his partner superfluous.
The male's partner plays an essential role in enabling him to overcome premature ejaculation. Without understanding and emotional support, the male is unlikely to obtain the level of relaxation required for sexual satisfaction. Both the male and his partner should communicate their feelings openly and with sensitivity. The male should learn to sexually satisfy his partner, orally or otherwise, while they work with him to overcome his premature ejaculation.
External latex rigid sheathes fastened to the body have been developed that cover all part of the penis during penetration so that the penis is protected from all the stimulation of the vagina. These help to gain control and to provide satisfaction to the partner.
[edit] Alternative therapies
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Many alternative therapies are available for the treatment of PE. Caution should be exercised when researching alternative sources of advice however, most treatments have not actually been shown to be effective. Some web sites even advocate the dangerous and antiquated method of pulling the testes downwards when aroused. This is actually a good way to slightly strain the interior of the testes and is associated with reports of injury and weakened/deteriorated erection. For some reason this advice is still widespread on the Internet.
Hypnosis has also proven very effective in the treatment of premature ejaculation.[citation needed] It is believed by some that ejaculation is a subconscious habit and by giving the mind hypnotic suggestions to last longer, the problem can be greatly alleviated if not completely cured.[citation needed] Most men report dramatic improvement after only a few sessions of hypnosis.
The prostate gland plays a very important part in regulating arousal. Pressure in between the engorged prostate and the erection causes most of the pleasurable sensations and it may be emptied manually before sex by prostate massage. This causes the erection to be strong but less sensitive, and increases a patients awareness of his physiology.
There is a trend toward the use of nutritional supplements when treating men who suffer from PE. Effective supplements must contain 5HTP which is a precursor to serotonin. A Dr. William Ganong, noted that serum serotonin levels could be increased through dietary means. Increasing the serum level of serotonin helps inhibit the ejaculatory reflex. There are a number of nutritional remedies available primarily on the Internet.
[edit] Diagnosis
Diagnostic criteria for Premature Ejaculation DSM-IV-TR (American Psychiatric Association)
A. Persistent or recurrent ejaculation with minimal sexual stimulation before, on, or shortly after penetration and before the person wishes it. The clinician must take into account factors that affect duration of the excitement phase, such as age, novelty of the sexual partner or situation, and recent frequency of sexual activity.
B. The disturbance causes marked distress or interpersonal difficulty.
C. The premature ejaculation is not due exclusively to the direct effects of a substance (e.g., withdrawal from opioids).
[edit] Differential diagnosis
Premature ejaculation should be distinguished from erectile dysfunction related to the development of a general medical condition. Some individuals with erectile dysfunction may omit their usual strategies for delaying orgasm. Others require prolonged noncoital stimulation to develop a degree of erection sufficient for intromission. In such individuals, sexual arousal may be so high that ejaculation occurs immediately. Occasional problems with premature ejaculation that are not persistent or recurrent or are not accompanied by marked distress or interpersonal difficulty do not qualify for the diagnosis of premature ejaculation. The clinician should also take into account the individual's age, overall sexual experience, recent sexual activity, and the novelty of the partner. When problems with premature ejaculation are due exclusively to substance use (e.g., opioid withdrawal), a substance-induced sexu al dysfunction can be diagnosed.
[edit] Associated conditions
Neurological disorders, e.g., multiple sclerosis
Prostatitis
Psychological disorders
Interpersonal disorders
ABC's Premature Ejaculation, e.g., [[2]]
[edit] See also
Delayed ejaculation
Drugs specifically targeted to treat premature ejaculation
From Wikipedia, the free encyclopedia
(Redirected from Premature Ejaculation)
Jump to: navigation, search
It has been suggested that Drugs specifically targeted to treat premature ejaculation be merged into this article or section. (Discuss) This article may require cleanup to meet Wikipedia's quality standards.
Please discuss this issue on the talk page or replace this tag with a more specific message.
This article has been tagged since May 2007.
Premature ejaculation (PE), also known as rapid ejaculation, premature climax, early ejaculation, or by the Latin term ejaculatio praecox, is the most common sexual problem in men, affecting 25%-40% of men. It is characterized by a lack of voluntary control over ejaculation. Masters and Johnson stated that a man suffers from premature ejaculation if he ejaculates before his partner achieves orgasm in more than fifty percent of his sexual encounters. Other sex researchers have defined premature ejaculation as occurring if the man ejaculates within two minutes or less of penetration; however, a survey by Alfred Kinsey in the 1950s demonstrated that three quarters of men ejaculated within two minutes of penetration in over half of their sexual encounters. Today, most sex therapists understand premature ejaculation as occurring when a lack of ejaculatory control interferes with sexual or emotional well-being in one or both partners.
Most men experience premature ejaculation at least once in their lives. Often adolescents and young men experience "premature" ejaculation during their first sexual encounters, but eventually learn ejaculatory control. Because there is great variability in both how long it takes men to ejaculate and how long both partners want sex to last, researchers have begun to form a quantitative definition of premature ejaculation. Current evidence supports a median average ejaculation latency time (IELT) of six and a half minutes in 18-30 year olds.[1] If the disorder is defined as an IELT percentile below 2.5, then premature ejaculation could be suggested by an IELT of less than about one and a half minutes. Nevertheless, it is well accepted that men with IELTs below 1.5 minutes could be "happy" with their performance and do not report a lack of control and therefore do not suffer from PE. On the other hand, a man with 2 minutes IELT could present with perception of poor control over his ejaculation, distressed about his condition, has interpersonal difficulties and therefore be diagnosed with PE.
Scientists have long suspected a genetic link to certain forms of premature ejaculation. In one study, ninety-one percent of men who suffered from lifelong premature ejaculation also had a first-relative with lifelong premature ejaculation. Other researchers have noted that men who suffer from premature ejaculation have a faster neurological response in the pelvic muscles. Simple exercises commonly suggested by sex therapists can significantly improve ejaculatory control for men with premature ejaculation caused by neurological factors[citation needed]. Often, these men may benefit from anti-anxiety medication or selective serotonin reuptake inhibitors (SSRIs), such as sertraline or paroxetine. Some men prefer using anaesthetic creams; however, these creams may also deaden sensations in the man's partner, and are not generally recommended by sex therapists.
Psychological factors also commonly contribute to premature ejaculation. While men sometimes underestimate the relationship between sexual performance and emotional well-being, premature ejaculation can be caused by temporary depression, stress over financial matters, unrealistic expectations about performance, a history of sexual repression, or an overall lack of confidence. Interpersonal dynamics strongly contribute to sexual function, and premature ejaculation can be caused by a lack of communication between partners, hurt feelings, or unresolved conflicts that interfere with the ability to achieve emotional intimacy. Neurological premature ejaculation can also lead to other forms of sexual dysfunction, or intensify the existing problem, by creating performance anxiety. In a less pathological context, premature ejaculation could also be simply caused by extreme arousal.
Some physical illnesses, such as a prostate infection, are also known to induce premature ejaculation. In other instances, premature ejaculation is caused by a physical injury that affects the nervous system. Certain medications, such as cold medications containing pseudoephedrine, also cause premature ejaculation. Sexual dysfunction is a common symptom of psychiatric afflictions ranging from bipolar disorder to post-traumatic stress disorder. In these cases, it is best to discuss the issues openly with a physician.
Today it is believed that the neurotransmitor serotonin (5HT) has a central role in modulating ejaculation. Several animal studies have demostrated its inhibitory effect on ejaculation modulated through the PGI system in the brain. Therefore, it is perceived that low level of serotonin in the synaptic cleft in these specific areas in the brain could cause premature ejaculation. This theory is further supported by the proven effectiveness of SSRIs, which increase serotonin level in the synapse, in treating PE.
Contents [hide]
1 Science of Mechanism of Ejaculation
2 Treatment
2.1 Alternative therapies
3 Diagnosis
3.1 Differential diagnosis
3.2 Associated conditions
4 See also
5 References
6 External Links
[edit] Science of Mechanism of Ejaculation
The process of ejaculation requires two sequentially distinct actions, emission and expulsion.
Mechanism of EjaculationThe emission phase is the first one to happen and it involves deposition of semenal fluid from ampullary vasa deferens, seminal vesicles & prostate gland into posterior urethra (Bohlen, et al., 2000). Second phase is the expulsion of semen which involves closure of bladder neck followed by the rhythmic contractions of urethra by pelvic-perineal and bulbospongiosus muscle and intermittent relaxation of external Sphincter urethrae (Master and Turek, 2001).
Sympathetic motor neurons control the emission phase of ejaculation reflex and expulsion phase is executed by somatic and autonomic motor neurons. These motor neurons are located in the thoracolumbar and lumbosacral spinal cord and are activated in a coordinated manner when sufficient sensory input to reach the ejaculatory threshold has entered the central nervous system (De Groat and Booth 1980; Truitt and Coolen 2002). Several areas in the brain, and especially the nucleus paragigantocellularis has been identified to be involved in ejaculatory control (Coolen, et al., 2004).
[edit] Treatment
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Depending on severity, premature ejaculation symptoms can be significantly reduced. In mundane cases, treatments are focused on gradually training and improving mental habituation to sex and physical development of stimulation control. In clinical cases, various medications are being trialled to help slow down the speed of the arousal response.
SSRI antidepressants have been shown to delay ejaculation in men treated for different psychiatry disorders. SSRIs are considered the most effective treatment currently available for PE. These include paroxetine, fluoxetine, sertraline and more. The use of these drugs, that require chronic therapy is limited by the neuropsychiatric side effects. New SSRI drugs specifically targeted to treat premature ejaculation (e.g. dapoxetine) can be taken on an as needed basis and have been recently shown positive results in large phase III studies. Nevertheless dapoxetine is not yet approved by any regulatory authority around the world. There is speculation that some of the associated effects are caused by lowered libido and blood pressure as well as lowered anxiety levels. Other pharmaceutical products known to delay male orgasm are; opioids, cocaine, and diphenhydramine.
The effects of hyperforin extract of Hypericum perforatum, has been evaluated on the ejaculatory reflex duration by using the intravaginal ejaculatory latency time (IELT) and sexual satisfaction (Cannon-Smith and Kaufman, 2007). In this trial sixteen men who desired longer sexual intercourse and without erectile dysfunction took with hypferforin immediately prior to sexual activity. All 16 participants completed the trial and there was a significant increase in mean ejaculation times from 246±29 to 331±34 seconds (p<0.002) in persons taking the hyperforin extract Prolasta. The increase was seen in both the men who reported PE as bothersome and those who did not feel that PE was a problem for them. The effect of Prolasta may be similar to that of dapoxetine.
Local anesthetic creams (like lidocaine, prilocaine and combinations) have shown to be very effective in clinical trials and are being used of the treatment of PE. Their use is limited by its own anesthetic effect that reduce sensation on the penis and vagina.
Most sex therapists prescribe a series of exercises to enable the man to gain ejaculatory control. While the exercises are intended for men who suffer from premature ejaculation, other men can use the exercises to enhance their sex lives. By far the most common exercise is the so-called start-stop technique. While the technique varies, the purpose is to get the male accustomed to maintaining an erection for an extended period of time while gradually increasing sexual tolerance. In doing this exercise, the male obtains an erection through self-stimulation, or masturbation. After achieving an erection, he stops stimulating himself until he begins to lose his erection; at that point, he begins to stimulate himself again. Gradually, over a period of several weeks, he is able to stimulate himself for longer periods of time, eventually gaining ejaculatory control. In order for this technique to be successful, the male should avoid feeling discouraged if he ejaculates rapidly; instead, he should use his sexual responses to learn how to vary the technique in a way that most benefits him. The male can choose to integrate his partner into these exercises.
The male's partner is usually integrated into the exercises. They can stimulate the partner using the stop-start technique. When the male has achieved some level of ejaculatory control, he can insert his penis into his partner without thrusting. After his penis becomes accustomed to being inside his partner, thrusting can be gradually included, according to the male's abilities, using the stop-start technique. In less severe cases, the male might overcome his premature ejaculation early on, making exercises with his partner superfluous.
The male's partner plays an essential role in enabling him to overcome premature ejaculation. Without understanding and emotional support, the male is unlikely to obtain the level of relaxation required for sexual satisfaction. Both the male and his partner should communicate their feelings openly and with sensitivity. The male should learn to sexually satisfy his partner, orally or otherwise, while they work with him to overcome his premature ejaculation.
External latex rigid sheathes fastened to the body have been developed that cover all part of the penis during penetration so that the penis is protected from all the stimulation of the vagina. These help to gain control and to provide satisfaction to the partner.
[edit] Alternative therapies
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Many alternative therapies are available for the treatment of PE. Caution should be exercised when researching alternative sources of advice however, most treatments have not actually been shown to be effective. Some web sites even advocate the dangerous and antiquated method of pulling the testes downwards when aroused. This is actually a good way to slightly strain the interior of the testes and is associated with reports of injury and weakened/deteriorated erection. For some reason this advice is still widespread on the Internet.
Hypnosis has also proven very effective in the treatment of premature ejaculation.[citation needed] It is believed by some that ejaculation is a subconscious habit and by giving the mind hypnotic suggestions to last longer, the problem can be greatly alleviated if not completely cured.[citation needed] Most men report dramatic improvement after only a few sessions of hypnosis.
The prostate gland plays a very important part in regulating arousal. Pressure in between the engorged prostate and the erection causes most of the pleasurable sensations and it may be emptied manually before sex by prostate massage. This causes the erection to be strong but less sensitive, and increases a patients awareness of his physiology.
There is a trend toward the use of nutritional supplements when treating men who suffer from PE. Effective supplements must contain 5HTP which is a precursor to serotonin. A Dr. William Ganong, noted that serum serotonin levels could be increased through dietary means. Increasing the serum level of serotonin helps inhibit the ejaculatory reflex. There are a number of nutritional remedies available primarily on the Internet.
[edit] Diagnosis
Diagnostic criteria for Premature Ejaculation DSM-IV-TR (American Psychiatric Association)
A. Persistent or recurrent ejaculation with minimal sexual stimulation before, on, or shortly after penetration and before the person wishes it. The clinician must take into account factors that affect duration of the excitement phase, such as age, novelty of the sexual partner or situation, and recent frequency of sexual activity.
B. The disturbance causes marked distress or interpersonal difficulty.
C. The premature ejaculation is not due exclusively to the direct effects of a substance (e.g., withdrawal from opioids).
[edit] Differential diagnosis
Premature ejaculation should be distinguished from erectile dysfunction related to the development of a general medical condition. Some individuals with erectile dysfunction may omit their usual strategies for delaying orgasm. Others require prolonged noncoital stimulation to develop a degree of erection sufficient for intromission. In such individuals, sexual arousal may be so high that ejaculation occurs immediately. Occasional problems with premature ejaculation that are not persistent or recurrent or are not accompanied by marked distress or interpersonal difficulty do not qualify for the diagnosis of premature ejaculation. The clinician should also take into account the individual's age, overall sexual experience, recent sexual activity, and the novelty of the partner. When problems with premature ejaculation are due exclusively to substance use (e.g., opioid withdrawal), a substance-induced sexu al dysfunction can be diagnosed.
[edit] Associated conditions
Neurological disorders, e.g., multiple sclerosis
Prostatitis
Psychological disorders
Interpersonal disorders
ABC's Premature Ejaculation, e.g., [[2]]
[edit] See also
Delayed ejaculation
Drugs specifically targeted to treat premature ejaculation
EATING DISORDER
ating disorder
From Wikipedia, the free encyclopedia
(Redirected from Eating disorders)
Jump to: navigation, search
Eating disorder
Classification & external resources ICD-10 F50.
ICD-9 307.5
MeSH D001068
An eating disorder is a complex compulsion to eat in a way which disturbs physical, mental, and psychological health. The eating may be excessive (compulsive over-eating); to limited (restricting); may include normal eating punctuated with episodes of purging; may include cycles of binging and purging; or may encompass the ingesting of non-foods. The most heard about eating disorders are Anorexia nervosa and Bulimia nervosa. The most widely and rapidly spreading eating disorder is compulsive overeating or Binge eating disorder. These are also the three most common eating disorders. All three have severe consequences to a person's immediate and long-term health and can cause death. There are numerous theories as to the causes and mechanisms leading to eating disorders.
Contents [hide]
1 Types
2 References
2.1 Journal references
2.2 Book reference
2.3 Online References
3 External links
[edit] Types
Anorexia nervosa
Starvation diet
Binge eating disorder
Bulimia nervosa
Diabulemia
Eating disorder not otherwise specified
Hyperphagia
Rumination
Pica
Night eating syndrome
Eating disorders are characterized by an abnormal obsession with food and weight. Eating disorders are much more noticed in women than in men. This can be attributed to the fact that society is seen to put an emphasis on woman to be thin, and men to be 'bulked up'. This can lead to pressure on woman to be 'picture perfect', and an eating disorder prevails as a result of stress of not being able to reach unattainable goals related to this 'picture perfect' ideal. Also, it can be due to the fact that men are less likely to seek help.
Many people with eating disorder can also have a comorbid diagnosis of one or more of the following: mood disorders and severe mental depression,[1] Obsessive compulsive disorder, Body dysmorphic disorder, Bipolar disorder, and self-harm.[2] The American Psychiatric Association lists eating disorders.
Some psychologists also classify a syndrome called orthorexia as an eating disorder, or, more properly, "disordered eating" - the person is overly obsessed with the consumption of what they see as the 'right' foods for them, to the point that their nutrition and quality of life suffers (although due to cultural and political factors which influence food choices, this idea is considered controversial by some). In addition, some individuals have food phobias about what they can and cannot eat, which can be characterised as an eating disorder. The UK broadcaster BBC3 have shown a series called Freaky Eaters that deals with such topics.
Somewhat qualitatively different from those conditions previously mentioned is pica, or the habitual ingestion of inedibles, such as dirt, wood, hair, etc.
From Wikipedia, the free encyclopedia
(Redirected from Eating disorders)
Jump to: navigation, search
Eating disorder
Classification & external resources ICD-10 F50.
ICD-9 307.5
MeSH D001068
An eating disorder is a complex compulsion to eat in a way which disturbs physical, mental, and psychological health. The eating may be excessive (compulsive over-eating); to limited (restricting); may include normal eating punctuated with episodes of purging; may include cycles of binging and purging; or may encompass the ingesting of non-foods. The most heard about eating disorders are Anorexia nervosa and Bulimia nervosa. The most widely and rapidly spreading eating disorder is compulsive overeating or Binge eating disorder. These are also the three most common eating disorders. All three have severe consequences to a person's immediate and long-term health and can cause death. There are numerous theories as to the causes and mechanisms leading to eating disorders.
Contents [hide]
1 Types
2 References
2.1 Journal references
2.2 Book reference
2.3 Online References
3 External links
[edit] Types
Anorexia nervosa
Starvation diet
Binge eating disorder
Bulimia nervosa
Diabulemia
Eating disorder not otherwise specified
Hyperphagia
Rumination
Pica
Night eating syndrome
Eating disorders are characterized by an abnormal obsession with food and weight. Eating disorders are much more noticed in women than in men. This can be attributed to the fact that society is seen to put an emphasis on woman to be thin, and men to be 'bulked up'. This can lead to pressure on woman to be 'picture perfect', and an eating disorder prevails as a result of stress of not being able to reach unattainable goals related to this 'picture perfect' ideal. Also, it can be due to the fact that men are less likely to seek help.
Many people with eating disorder can also have a comorbid diagnosis of one or more of the following: mood disorders and severe mental depression,[1] Obsessive compulsive disorder, Body dysmorphic disorder, Bipolar disorder, and self-harm.[2] The American Psychiatric Association lists eating disorders.
Some psychologists also classify a syndrome called orthorexia as an eating disorder, or, more properly, "disordered eating" - the person is overly obsessed with the consumption of what they see as the 'right' foods for them, to the point that their nutrition and quality of life suffers (although due to cultural and political factors which influence food choices, this idea is considered controversial by some). In addition, some individuals have food phobias about what they can and cannot eat, which can be characterised as an eating disorder. The UK broadcaster BBC3 have shown a series called Freaky Eaters that deals with such topics.
Somewhat qualitatively different from those conditions previously mentioned is pica, or the habitual ingestion of inedibles, such as dirt, wood, hair, etc.
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