Oncologist-approved cancer information from the American Society of Clinical Oncology
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This section has been reviewed and approved by the Cancer.Net Editorial Board, 3/2013

ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Mesothelioma. To see other pages, use the colored boxes on the right side of your screen. Think of those boxes as a roadmap to this full guide. Or, click “Next” at the bottom of each page.

Cancer begins when normal cells change and grow uncontrollably, forming a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body).

Mesothelioma is a rare cancer that begins in the lining of different internal organs of the body. Approximately three-fourths of mesotheliomas begin in the lining surrounding the lungs, called pleural mesothelioma. While pleural mesothelioma does begin in the chest cavity, it does not start in the lungs, and it is often incorrectly grouped with lung cancer. Mesothelioma that begins in the tissue surrounding the abdominal area, called peritoneal mesothelioma, accounts for about 10% to 20% of mesotheliomas. The rarest types of mesothelioma begin in the lining around the heart (called pericardial) or around a man’s testicles (called tunica vaginalis).

There are three main types of mesothelioma:

Epithelioid type. About 70% of people diagnosed with mesothelioma have the epithelioid type. Epithelioid mesothelioma may grow slower and treatment often works better for this type.

Sarcomatoid type. Between 7% to 20% of people diagnosed with mesothelioma have the sarcomatoid type. This type has a worse prognosis (chance of recovery) than the other two types. Chemotherapy for sarcomatoid mesothelioma does not often work well to treat the cancer.

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. People with this type have a worse prognosis than those with the epithelioid type but a better prognosis than those with the sarcomatoid type.

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