Mesothelioma is cancer of the mesothelium, a protective membrane that lines most of the body’s internal organs. Three out of every four cases cases of mesothelioma disease begin in the pleural mesothelium of the chest cavity. Mesothelioma can also begin in the abdominal cavity and around the heart.
Regardless of where they originate, malignant cells from the mesothelium can invade and damage nearby tissues. Cancer cells can also metastasize, or spread, to other parts of the body.
Often by the time mesothelioma is diagnosed, the disease is advanced. The five-year survival rate is around 5% to 10%. Most patients with mesothelioma die as a result of respiratory failure or pneumonia. Some patients develop a small-bowel obstruction when a tumor extends through the diaphragm. A smaller number die of cardiac complications when the tumor invades the pericardium — the thin membrane that surrounds the heart — and the heart itself.
Mesothelioma is a relatively rare form of cancer. About 3,000 new cases of the disease are diagnosed in the U.S. each year.