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).

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

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.

How is mesothelioma diagnosed?

No laboratory test can specifically diagnose mesothelioma, but there are a number of ways to tell if someone has the condition, including the following:

  • Physical exam and history – The doctor will check the patient’s general health and look for signs of disease, such as lumps or any other unusual symptoms. The doctor will also ask questions about health habits, exposure to asbestos, past illnesses, and treatments.
  • Chest computed tomography (CT) scan – Can show abnormal growths or thickening of tissue inside the chest cavity.
  • Positron emission tomography (PET) scan – Can show if the disease is metastasizing (spreading).
  • Complete blood count (CBC) – A blood sample to check on red and white blood cell counts and certain antibodies (disease-fighting proteins)
  • Biopsy – Removal of tissue from the lining of the chest or abdomen to search for cancer cells under a microscope. A biopsy can be done by either using a thin needle or by making a small cut to take out the tissue needed.
  • Bronchoscopy – Insertion of a bronchoscope through the nose or mouth into the trachea (windpipe) and lungs. The bronchoscope is a tube-like device with a light and a lens for viewing structures inside the airways. It may also have a tool that can take tissue samples.
  • Cytologic exam – Fluid is taken from around the lungs or abdomen and checked under a microscope.

How is mesothelioma treated?

  • Surgery
    • Wide local excision – Taking out cancerous tissue and some healthy surrounding tissue
    • Pleurectomy and decortication – Taking out some of the covering of the lungs, the lining of the chest, and part of the outside surface of the lungs
    • Extrapleural pneumonectomy – Taking out one whole lung and part of the lining of the chest, the diaphragm, and the lining of the sac around the heart
    • Pleurodesis – Using chemicals or drugs to cause scarring in pleural tissue, which stops the buildup of fluid in the pleural cavity
  • Radiation therapy – Using X-rays or other kinds of radiation to kill cancer cells, usually following surgery. It is very difficult to surgically remove all the tissue affected by mesothelioma.
  • Chemotherapy – Using drugs (a pill that is swallowed or an injection directly into a vein or muscle) to stop the growth of cancer, either by killing the cells or stopping them from dividing

What is the prognosis (chance for recovery) for someone with mesothelioma?

There is no known cure for mesothelioma; only about 15% of such patients are able to survive five years or longer.

Surgery appears to improve survival rates, but only in that small number of patients who get treatment at an early stage, and who are otherwise healthy enough to undergo such procedures.

Most patients are not diagnosed at an early stage because symptoms may not appear until later. Also, because of the nature of mesothelioma, it tends to involve most of the lining of the lung when it is found. Chemotherapy is often the main treatment and has been shown to prolong survival and improve quality of life for patients with mesothelioma.

What can be expected after treatment for mesothelioma?

Following treatment, tests that were first used to diagnose or learn the stage of cancer may be repeated. These retests will help determine how well treatments have worked, whether the condition has changed, whether different treatments should be tried, and whether the cancer has come back.

How can mesothelioma be prevented?

Here are some ways to prevent exposure to asbestos:

  • Wear protective gear at jobs that have known exposure to asbestos.
  • Leave clothes that are worn while working with asbestos at the work site.
  • Wear protective gear when doing home renovations, especially on homes built before 1980.
  • Make sure that sources of asbestos in older homes (such as insulation, roof shingles, drywall, floor tiles, and wrapping on pipes) do not crumble because of age. If these sources are to be sealed up or removed, the work should be done by workers trained to deal with asbestos.

References

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 2/3/2016…#15044