What Is Malignant Mesothelioma?

Malignant mesothelioma is a cancer that starts in cells in the linings of certain parts of the body, especially in the linings of the chest or abdomen.

A layer of specialized cells called mesothelial cells lines the inside of the chest, the abdomen, and the space around your heart. These cells also cover the outer surface of most of your internal organs. The lining formed by these cells is called the mesothelium.

The mesothelium helps protect your organs by making a special lubricating fluid that allows organs to move against each other. For example, this fluid makes it easier for your lungs to move (expand and contract) inside the chest when you breathe. The mesothelium has different names in different parts of the body:

  • The pleura coats the lungs and the space in the chest containing the lungs.
  • The peritoneum lines the inside of the abdomen and many of the organs in the abdomen.
  • The pericardium covers the heart and creates the space that holds the heart in the chest.
  • The tunica vaginalis lines the testicles.

Mesothelial tumors can start in any of these linings. These tumors can be non-cancerous (benign) or cancerous (malignant).

A cancerous tumor of the mesothelium is called a malignant mesothelioma, although this is often shortened to just mesothelioma. Mesotheliomas can start in 4 main areas in the body.

  • Pleural mesotheliomas start in the chest. About 3 out of 4 mesotheliomas are pleural mesotheliomas.
  • Peritoneal mesotheliomas begin in the abdomen. They make up most of the remaining cases.
  • Pericardial mesotheliomas start in the covering around the heart and are very rare.
  • Mesotheliomas of the tunica vaginalis are very rare tumors that start in the covering layer of the testicles.

Malignant mesotheliomas can also be classified into 3 main types based on how the cancer cells are arranged:

  • About half of mesotheliomas are epithelioid. This type tends to have a better outlook (prognosis) than the other types.
  • About 10% of mesotheliomas are sarcomatoid (fibrous).
  • Mixed (biphasic) mesotheliomas have both epithelioid and sarcomatoid areas. They make up the remaining 30% to 40% of mesotheliomas.

After the cancer is found and staged with the help of CT Scans and PET scan, your cancer care team will discuss your treatment options with you. The main factors in selecting treatment for mesotheliomas are the location and extent of the tumor, whether it has spread to lymph nodes or other organs, and your health and personal preferences. Based on these factors, your treatment options may include:

  • Surgery
  • Radiation therapy
  • Chemotherapy

Mesothelioma can be hard to treat because it typically does not grow as a single tumor mass. It tends to spread along nearby surfaces, nerves, and blood vessels. This often makes it very hard to get rid of the cancer completely with surgery and/or radiation. For some people, palliative procedures might be used to help treat some symptoms of mesothelioma.

Because mesothelioma is a rare cancer, it has been hard for doctors to compare the value of different treatments. Only a few large clinical trials of treatments for mesothelioma have been done. In addition, many doctors have very little experience treating this disease. They usually refer patients to specialists who treat large numbers of mesothelioma patients at major medical centers.

You might have different types of doctors on your treatment team, depending on the stage of your cancer and your treatment options. These doctors may include:

  • thoracic surgeon: a doctor who treats diseases of the lungs and chest with surgery
  • surgical oncologist: a doctor who treats cancer with surgery
  • radiation oncologist: a doctor who treats cancer with radiation therapy.
  • medical oncologist: a doctor who treats cancer with medicines such as chemotherapy
  • pulmonologist: a doctor who specializes in medical treatment of diseases of the lungs

Usual treatment consists of chemotherapy along with newer treatment options of targeted therapy, immunotherapy. Surgery can be done when it is localized.