Mesothelioma is a form of cancer, benign or malignant, that affects the mesothelium, a membrane that covers most of the body's internal organs. Most cases of mesothelioma begin in the pleura, the lining around the lungs, or peritoneum, the lining around the abdomen. This disease is almost always caused by exposure to asbestos.

Asbestos is a name given to naturally occurring silicate minerals that have been mined for its useful properties, such as thermal insulation and chemical and thermal stability.

Those who develop malignant mesothelioma have worked on jobs where they have inhaled asbestos particles.