Overview

Mesothelioma is a rare cancer that begins in the lining of the internal organs of the body. Approximately three-fourths of cases of mesothelioma 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 cases.

There are three main types of mesothelioma:

Epithelial type. The epithelial type accounts for 50% to 70% of people diagnosed with mesothelioma. It has the best prognosis (chance of recovery) due to its slower growth, and this type is more likely to respond to treatment.

Sarcoma type. The sarcoma type accounts for 7% to 20% of people diagnosed with mesothelioma and has a worse prognosis.

Mixed type. The mixed type accounts for 20% to 35% of people diagnosed with mesothelioma and contains both epithelial and sarcomatous types. This type of mesothelioma has an intermediate prognosis.

Cancer begins when cells become abnormal, grow uncontrollably, and eventually form a tumor. Tumors can be benign (non-cancerous) or malignant (cancerous, meaning it can spread to other parts of the body). This section covers malignant mesothelioma.

Statistics

It is estimated that 2,000 to 3,000 cases of mesothelioma are diagnosed each year in the United States. Mesothelioma occurs more frequently in men, and thee-fourths of people with mesothelioma are over age 65.

While mesothelioma rates have increased in previous decades, they have since stabilized in the United States and may be decreasing. The five-year relative survival rate (percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) of people with mesothelioma is about 10%. The average survival for a person with mesothelioma is about one to two years. These numbers reflect the fact that most cases are advanced at the time of diagnosis.

However, cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with mesothelioma. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer.

Source: American Cancer Society

Find out more about basic cancer terms used in this section.