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Mesothelioma Symptoms, Causes and Risk Factors

Mesothelioma generally occurs in people who have previously been exposed to asbestos, sometimes 40 to 60 years prior to the diagnosis. In most cases, mesothelioma occurs at least 20 years after asbestos exposure. Those who get mesothelioma are usually exposed to higher levels of asbestos than those who get other asbestos-related disease, including lung scarring (fibrosis) and lung cancer.

What Are the Symptoms of Mesothelioma?

Less than 5 percent of individuals exposed to asbestos will eventually develop mesothelioma. Sometimes, the diagnosis is discovered on a chest- X-ray done for other reasons.

The most common symptoms are:

The progression of the cancer can also result in general symptoms such as:

  • Weight loss with low appetite
  • Generalized fatigue
  • Low grade fever

When other areas of the body are affected by mesothelioma, other localized symptoms may occur:

  • When the peritoneum (lining on the abdomen) is involved, abdominal swelling, constipation, intestinal obstruction and pain and nausea may occur.
  • An abnormal mass or swelling may be felt in the scrotum when its lining is involved

Rarely, the defense mechanisms of the body may try to control the disease by producing antibodies aimed at fighting the cancer that can themselves lead to symptoms, such as hypoglycemia, blood clots in the legs or the lungs and various neurological symptoms. These symptoms are called "paraneoplastic" which means "associated with cancer."

What Causes Mesothelioma?

Researchers are still trying to understand what causes mesothelioma, other than as a response to asbestos fibers over a long period of time.

What Is Asbestos?

When an individual is exposed to asbestos, the small fibers can easily be inhaled into the lungs, increasing the risk of developing mesothelioma, lung cancer and a type of scarring lung disease called asbestosis.

What Are the Risk Factors?

  • Asbestos exposure: Asbestos is a mineral fiber that resists fire and heat, and has been used in insulation and fire retardant materials. Concerns over human safety appeared at the beginning of the 20th and its use was finally banned or tightly regulated in most countries 30 years ago. Most individuals who develop mesothelioma due to asbestos were exposed during their work, called an "occupational exposure". The typical occupations associated with exposure to asbestos include mining or milling, electricians, plumbers, pipe-fitters, insulators and even individuals who have remodeled older homes or lived with workers exposed to asbestos. Living in a house that contains asbestos is not generally considered to be a cause of mesothelioma when the asbestos is enclosed in walls and ceilings, and not directly breathed by individuals.
  • Smoking is not a risk factor for mesothelioma; however, quitting smoking is extremely important: asbestos exposure does not increase the risk of mesothelioma, but does increase the risk of lung cancer in general.
  • Other types of fibers, such as erionite, are thought to be responsible for mesothelioma, as well. Erionite has been identified in a specific region in Turkey called Cappadocia and is thought to be responsible for the high rate of mesotheliomas observed in that area.
  • Age: The risk of developing mesothelioma increases with age. This is due to the fact that it takes a long time for mesothelioma to develop after asbestos exposure, usually at least 20 years. This length of time from exposure to malignancy is called latency.
  • Other causes have been discovered, including prior radiation therapy, particularly in patients who have received high doses of radiation therapy to the chest for cancer, such as in the treatment of lymphoma, and certain rare genetic mutations. These causes are much less common than asbestos exposure.
  • Sometimes, no cause can be identified at all.

When to See Your Doctor

If you have been exposed to asbestos at work or somewhere else, have been diagnosed with frequent pneumonias, or experience the symptoms listed above, you should consult your healthcare provider.

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

    Last updated April 4, 2018.

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