Learn About Mesothelioma | American Lung Association

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Learn About Mesothelioma

Mesothelioma is a rare type of cancer that develops in the pleura, a thin membrane that separates the lung from the chest wall. As it progresses along the membrane, it results in breathing difficulties, chest pain and fever. It usually occurs from prior exposure to asbestos, a type of mineral fiber used in the insulation industry. Less commonly, mesothelioma can also arise, less commonly, along the lining of the abdomen.

Key Facts:

  • Mesothelioma is a rare type of cancer that usually arises from the lining of the lung (pleura) and less commonly the lining of abdomen (peritoneum).
  • Although patients with mesothelioma have been exposed to asbestos, only a small fraction of patients with exposure develop the disease.
  • Mesothelioma is not caused by smoking.
  • Other causes have been identified, and sometimes it is unclear what causes a person to get mesothelioma.

What Is Mesothelioma?

There are approximately 3,500 new cases of mesothelioma every year in the United States.  This is a very small number compared to lung cancer (220,000 new cases per year in the United States). It is caused by exposure to asbestos in at least 80 percent of the cases, and in some, there is probably exposure that a patient may not know about. When asbestos fibers are inhaled into the lung, they can penetrate very deeply due to their small size and accumulate near the lining of the lung, or pleura. These fibers can irritate the pleura resulting in inflammation and abnormal growth of mesothelial (surface lining) cells, which can eventually lead to cancer. The abnormally growing mesothelial cells produce tumor nodules on the surface of the lung and cause fluid accumulation (pleural effusion) between the lung and the chest wall resulting in pain and shortness of breath. There are other areas in the body with a lining similar to the pleura that can also be affected, although much less commonly. 

How Mesothelioma Affects Your Body

Mesothelioma, unlike other cancers, tends to grow mainly along the surface of the lung and other surfaces of the chest resulting in pain from invasion of nerves, and shortness of breath from compression of the lungs or restriction of lung expansion. Tumor nodules and fluid accumulates along the pleural space between the lung and the chest wall. Sometimes the growth of the tumor leads to fever. Though mesothelioma can spread to chest lymph nodes and invade into the lung, it is rare for it to spread to the rest of the body. Left untreated, mesothelioma worsens and can cause death.

How Serious Is Mesothelioma?

Mesothelioma is a very serious disease. While promising research efforts are underway, there is currently no consistently effective treatment for this disease. However, treatment to ease symptoms, sometimes called palliative or supportive care, can often control debilitating symptoms. The severity of mesothelioma can vary from person to person.


    This content was developed in partnership with the CHEST Foundation, the philanthropic arm of the American College of Chest Physicians.


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