Mesothelioma

Approved by the Cancer.Net Editorial Board, 09/2020

Mesothelioma is a rare cancer that begins in the lining of different internal organs of the body.

Approximately 75% to 80% of mesotheliomas begin in the lining surrounding the lungs. This is called pleural mesothelioma. Pleural mesothelioma begins in the chest cavity. It does not start in the lungs and it is often incorrectly called a lung cancer.

Peritoneal mesothelioma begins in the tissue surrounding the abdominal area, called the peritoneum. About 8% of mesotheliomas are peritoneal mesothelioma.

Rare types of mesothelioma can also begin in the lining around the heart, called the pericardium, or in the lining around the testicles, called the tunica vaginalis.

There are 3 main types of mesothelioma:

• Epithelioid type. About 70% of people diagnosed with mesothelioma have the epithelioid type. Epithelioid mesothelioma may grow slower and chemotherapy often works better for this type.
• Sarcomatoid type. Between 7% to 15% of people diagnosed with mesothelioma have the sarcomatoid type. Sarcomatoid mesothelioma may be more resistant to treatment compared with the other 2 types of mesothelioma. Standard chemotherapy often does not work well for this type of mesothelioma.
• Mixed, or biphasic, type. Between 10% to 20% of people diagnosed with mesothelioma have the mixed type. The term “mixed” or “biphasic” means that the cancer contains both epithelioid and sarcomatoid types. Treatment does not work as well for this type when compared with the epithelioid type. However, treatment for this type often works better than for the sarcomatoid type.