Cancer begins when healthy cells change and grow uncontrollably, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.
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 the pericardium, or around a man’s testicles, called the tunica vaginalis.
Types of mesothelioma
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. People with this type often have a lower chance of recovery compared with the other two types. Chemotherapy for sarcomatoid mesothelioma does not often work well.
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 less of a chance of recovery compared with those who have the epithelioid type, but they have a higher chance of recovery compared with those who have the sarcomatoid type.