Mesothelioma

Tumors of the mesothelium can be either benign (non-cancerous) or malignant (cancerous). Since malignant mesothelioma is much more common than benign mesothelioma it is often simply called mesothelioma. Characteristics of a malignant tumor are that it has the ability to spread to other parts of the body, making it much more dangerous.

Malignant mesothelioma is divided into three types: epithelioid, sarcomatoid, and mixed/biphasic. 50% to 70% of mesothelioma cases are epithelioid, which also has the best prognosis (outlook for survival). 7% to 20% are of the sarcomatoid type, and 20% to 35% are the mixed/biphasic type. Epithelioid affects the membranous tissue covering internal organs and other internal surfaces of the body. Sarcomatoid arises from supportive tissue, such as bone, muscles, cartilage, or fat. Biphasic mesothelioma has features of both epithelioid and sarcomatoid. The treatment options are the same for each type.

Approximately three-fourths of mesothelioma cases start in the chest cavity and are known as pleural mesothelioma. Another 10% to 20% begin in the abdomen and are called peritoneal mesothelioma. Those starting in the cavity around the heart, or pericardial mesothelioma, are very rare. The covering layer of the testicles is actually an outpouching of peritoneum into the scrotum. Mesothelioma that affects this covering of the testicles is quite uncommon.

Mesothelioma is still fairly rare. There are about 2,000 to 3,000 new cases per year in the United States. Most of the people who are diagnosed with malignant mesothelioma are over fifty years old and is seen more often with people in their seventies, since they were exposed to asbestos in the 1940s-50s or earlier. Those who were exposed to asbestos in the 1960s-70s may be diagnosed in years to come. The disease attacks men 3 to 5 times more than women. Men are more likely then women to get this disease because men held more construction positions than women in past decades (before the women's rights movement had taken place). Mesothelioma is also more common to Caucasians than in African Americans. Even though this disease is rare it is very serious. By the time it is diagnosed it is often in its advanced stages, making the outlook not as good as it is for other cancers that are found earlier. The average survival time is about 1 to 2 years after being diagnosed. Of course, survival rates are increasing due to advances in medical technology and new treatments that are being developed for mesothelioma.