Mesothelioma is an aggressive cancer that affects the lining of the lungs, heart, or abdomen. Although rare, mesothelioma is a very aggressive cancer which is difficult to treat. Its main risk factor is long-term exposure to asbestos. Asbestos exposure is most common in people working in the mining, textile, construction and ship building industries. It takes many decades to develop mesothelioma and this type of cancer is more commonly diagnosed in men over 70 years of age. Every year in the United States close to 3,000 people are diagnosed with mesothelioma. Depending on the stage of the cancer at the time of diagnosis, the average life expectancy of mesothelioma patients varies from 4-18 months. The diagnosis is commonly delayed because the symptoms of mesothelioma are nonspecific such as a cough, difficulty in breathing, fatigue, loss of appetite, and abdominal or chest pain. At the present time, the only treatments available for malignant mesothelioma are surgery, chemotherapy and radiation, and none of them cure mesothelioma.