Mesothelioma is an uncommon form of cancer. It involves the cells that line an organ, usually the lungs, abdominal organs, and heart—known as the mesothelium. In the most common form of mesothelioma, tumors form on the sac that lines the chest cavity and protects the lungs. Most people who have mesothelioma have been exposed to asbestos at work. But not everyone who is heavily exposed to asbestos at work develops mesothelioma or other diseases related to asbestos. Researchers are working to find new treatments for mesothelioma.

The American Lung Association can help you learn more about mesothelioma.