Mesothelioma is a form of cancer that is almost always caused by exposure to asbestos. In this disease, malignant cells develop in the mesothelium, a protective lining that covers most of the organs. The most common site is the pleura (the outer layer of the lungs and internal chest wall), but also can occur in the peritoneum (abdominal cavity lining), heart, pericardium (the sac that surrounds the heart) or tunica vaginalis.
Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles, or they have been exposed to asbestos dust and fibers in other ways. It has also been suggested that washing the clothes of family members who worked with asbestos can put someone at risk for mesothelioma. Unlike lung cancer, no association between mesothelioma and smoking, but smoking greatly increases the risk of other cancers caused by asbestos. Compensation via asbestos funds or lawsuits is an important issue in mesothelioma (see asbestos and the law).
Mesothelioma symptoms include shortness of breath due to pleural effusion (fluid between the lung and the chest wall) or chest wall pain, and general symptoms such as weight loss. Diagnosis can be suspected with chest X-ray and CT scan, and confirmed with a biopsy (tissue sample) and microscopic examination. A thoracoscopy (inserting a tube with a camera into the chest) can be used to take biopsies. This allows the introduction of substances such as talc to obliterate the pleural space (called pleurodesis), which prevents more fluid from collecting and pressing on the lung. Despite treatment with chemotherapy, radiation therapy or sometimes surgery, the disease carries a poor prognosis. Research about screening tests for early detection of mesothelioma is ongoing.