Mesothelioma

Malignant mesothelioma is a rare cancer that occurs in the thin layer of tissue that covers the majority of your internal organs (mesothelium). Doctors divide mesothelioma into different categories based on what part of the mesothelium is affected by cancer. Mesothelioma that occurs in the tissue that surrounds the lung (pleura) is called pleural mesothelioma and is the most common form. Mesothelioma that occurs in the tissue in your abdomen (peritoneum) is called peritoneal mesothelioma and accounts for 10 percent to 20 percent of all mesotheliomas. In rare cases, mesothelioma can also occur in the lining around the heart (pericardium) and in the lining around the testicles (tunica vaginalis).

Between 2,000 and 3,000 people are diagnosed with mesothelioma in the United States each year. Men are more likely to develop mesothelioma than are women. It's more common in older adults — most people with mesothelioma are 65 and older — though mesothelioma can be diagnosed at any age.

Mesothelioma is closely linked to exposure to asbestos — a natural fiber that was once used in manufacturing a wide variety of industrial and household products. Mesothelioma rates have increased during the past 20 years in response to the widespread use of asbestos in the past. Many industrialized countries now limit asbestos use and enforce laws to protect workers who may be exposed. Researchers predict these efforts will lead to fewer cases of mesothelioma in the future.