What is mesothelioma?

Malignant pleural mesothelioma is a rare type of cancer in which malignant (cancerous) cells are found in the pleura (the thin layer of tissue lining the chest cavity and covering the lungs) or the peritoneum (the thin layer of tissue lining the abdomen and covering most of the internal organs).

How common is mesothelioma?

Mesothelioma is a rare cancer, with about 2,000 to 3,000 new cases per year. (In comparison, there are more than 200,000 new cases of lung cancer per year.) Asbestos exposure in the United States peaked in the years from 1940 to 1980. Many disease cases have developed over the past 50 years due to exposure years ago.

Asbestos still exists in older homes and buildings, and fibers can be released if material is loose, crumbling, or disturbed. Asbestos is still used in brake pads, clutches, roofing material, vinyl tile, and some cement pipe. Also, rocks in certain parts of the United States have asbestos that can be released when disturbed or as they weather.

What causes mesothelioma?

Many people with mesothelioma have either inhaled or swallowed asbestos fibers. While nearly everyone has come into contact with asbestos, those who become sick from it have usually had frequent exposure to high levels over a long period of time. This happens in occupations like shipbuilding, pipefitting, construction, and auto repair (asbestos is used in brakes).

It is also possible to breathe in or swallow asbestos fibers at home if such material comes apart during use, demolition work, construction, or home maintenance, repair, or remodeling. Simply living with someone who has worked with asbestos and brought home fibers on their clothing, shoes, or body can also be a source of exposure.

Asbestos is a natural mineral whose fibers cannot be seen by the naked eye. Fibers come in two forms: serpentine fibers are spiral-shaped, while amphibole fibers look like a needle. It is believed that mesothelioma is caused by amphibole fibers burrowing into tissue, causing long-lasting irritation that leads to the development of cancerous cells. It may take 20 to 30 years after exposure to asbestos before mesothelioma develops.

Besides asbestos, other, less common causes of mesothelioma include exposure to high levels of radiation or an infection from a virus found in monkeys.

What are the symptoms of mesothelioma?

People who have mesothelioma may not have symptoms right away. When symptoms do appear, it is often in the disease’s later stages. Symptoms include:

  • Shortness of breath, caused by fluid buildup around the lungs
  • Dull chest ache or pain under the rib cage
  • Pain or swelling in the abdomen (belly)
  • Lumps in the abdomen
  • Weight loss for no known reason

Last reviewed by a Cleveland Clinic medical professional on 01/29/2016.


  • Raja S, Murthy SC, Mason, DP: Malignant Pleural Mesothelioma. Curr Oncol Rep DOI 10.001/s11912-011-0177-9. Springer Science+Business Media LLC, 2011.
  • Ai, J., Stevenson, J.P. Current issues in malignant pleural mesothelioma evaluation and management. Oncologist. 2014:19;975-984.
  • Agency for Toxic Substances & Disease Registry. Living with Asbestos Accessed 2/3/2016.
  • National Cancer Institute. Malignant Mesothelioma Treatment Accessed 2/3/2016.

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