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What is Mesothelioma?
Malignant pleural mesothelioma (MPM) is a rare form of cancer that originates in the pleura, the membrane which lines the chest cavity. Most cases of mesothelioma are related to exposure to asbestos, a naturally occurring fibrous mineral used extensively in the past in the construction, automotive and manufacturing industries.
 Asbestos fibers are easily inhaled, and tend to settle in the lower portions of the lung near the pleura. The fibers can cause inflammation and scarring and lead to lung damage or asbestosis. Occasionally, asbestos fibers cause changes to occur in the pleura, leading to the development of MPM 15 to 45 years after exposure.
Because of this long latency period, many of the 2,000-3,000 cases diagnosed annually in the United States are patients who had been exposed to asbestos many years earlier while working at shipbuilding or naval yards, or in mechanical, insulation or manufacturing industries.
Men are three to five times more likely to develop mesothelioma than women. There are three cell types of mesothelioma:
Epithelioid accounts for 50% to 70% of all cases. It also has the best prognosis.
Sarcomatoid accounts for 10% to 15% of all cases. It is a more aggressive form of mesothelioma.
Biphasic or Mixed accounts for 10% to 15% of cases. This form has characteristics of both epithelioid and sarcomatoid mesotheliomas but is associated with worse survival than epithelioid mesothelioma. | 
