Mesothelioma

Mesothelioma (me-zo-thee-le-O-muh), also called malignant * mesothelioma, is a rare, deadly cancer * of the mesothelium * —the tissue that lines the lungs, stomach, heart, and other organs. Most mesotheliomas are caused by exposure to asbestos.

What Is Mesothelioma?

Mesothelium is the two-layered membrane * that covers most of the organs of the body. It produces a lubricating fluid between the layers that cushions the organs and permits movement. Mesotheliomas can originate in four different types of mesothelium:




Mesothelioma is a rare form of cancer that is most commonly caused by exposure to asbestos.





Mesothelioma is a rare form of cancer that is most commonly caused by exposure to asbestos.
Spencer Sutton/Science Source.

There are three types of mesothelioma:

Although most people who develop mesothelioma have lived or worked where they may have inhaled or swallowed asbestos, the cancer can take 20 to 50 years to develop. Household members of people who worked with asbestos are also at risk for mesothelioma. However, many people with prolonged asbestos exposure never develop the disease, whereas some people with no known exposure do. There is some evidence that genetic * susceptibility * may play a role in mesothelioma. Some studies have suggested the possibility that exposure to simian virus * 40 (SV40) may increase one's risk for mesothelioma. Some injectable polio vaccines manufactured between 1955 and 1963 were contaminated with SV40, potentially affecting an estimated 10 to 30 million people.

How Common Is Mesothelioma?

Although it remains a relatively rare cancer, the incidence *

Who Has Been Exposed to Asbestos?

Workers at risk for asbestos exposure include:

  • Asbestos miners and millers
  • Manufacturers of asbestos textiles and other products
  • Construction workers who handle insulation
  • Drywall removers
  • Demolition workers
  • Firefighters
  • Shipbuilders
  • Automobile workers
  • Railroad workers

Living near asbestos mines or deposits is also a risk. Libby, Montana, is believed to have the highest rate of mesothelioma in the United States because of the W.R. Grace vermiculite mine that operated near the town until 1990.

WHAT IS ASBESTOS?

Asbestos is a group of naturally occurring fibrous silicate minerals. Small amounts of asbestos are present in the air, soil, and water. Curly chrysotile asbestos fibers are the predominant type used in commercial applications. Amphibole asbestos has straight needle-like fibers that may pose a greater risk for mesothelioma because they tend to remain in the lungs longer.

Starting in the late 1800s asbestos was mined for use in numerous industrial products, including cement, plastics, roofing, insulation, floor coverings, ceiling tiles, fireproofing, paints, coatings, adhesives, and textiles. It was used in the shipbuilding and automotive industries. However, there was a health risk in these uses. Tiny particles of asbestos that become airborne during manufacturing processes can be inhaled or swallowed, causing a range of serious health problems, including mesothelioma and other cancers.

In the early 1940s industrial use of asbestos increased sharply, and millions of Americans were exposed to asbestos dust. Because of the rise in mesothelioma and other diseases among asbestos workers, the Occupational Safety and Health Administration (OSHA) set limits on workplace exposure, and workers began wearing protective clothing and equipment. Workers were later usually required to shower and change clothing before leaving the workplace, to avoid bringing asbestos dust home on clothing, shoes, skin, and hair.

In the late 1970s, the Consumer Product Safety Commission banned the use of asbestos in wallboard patching compounds and gas fireplaces. In 1979, electric hairdryer manufacturers voluntarily abandoned their use of asbestos. In 1989, the Environmental Protection Agency (EPA) banned all new uses of asbestos. The EPA also required schools to remove or encase damaged asbestos. The EPA estimates that as many as 733,000 schools and public buildings in the United States contain asbestos insulation. U.S. manufacturers voluntarily eliminated asbestoscontaining talcs from crayons, and the EPA recommended caution when using vermiculite-containing garden products. Domestic use of asbestos dropped from 803,000 metric tons in 1973 to 950 metric tons in 2013.

What Are the Symptoms of Mesothelioma?

Early symptoms of mesothelioma are nonspecific and often overlooked. More than half of people with pleural mesothelioma complain of pain in the lower back or side of the chest. Other symptoms of mesothelioma include:

HOW DOES ASBESTOS CAUSE MESOTHELIOMA?

Asbestos is a known human carcinogen. When asbestos breaks up—as during mining or insulation removal—the airborne dust can be inhaled or swallowed. Tiny fibers travel to ends of small air passages, reaching the pleura. There the fibers cause scarring and inflammation * of mesothelial cells and stimulate their growth. The fibers may damage the cells’ DNA * , leading to uncontrolled growth. Peritoneal mesothelioma can result from coughing up and swallowing inhaled asbestos fibers.

Since asbestos fibers remain in the body, the mesothelioma risk does not drop with time. The risk does depend on the level and duration of exposure. People exposed to high levels for a long period at a young age are most at risk.

Will 9/11 Result in Increased Mesotheliomas?

Rescue, recovery, and cleanup workers at the site of the September 11, 2001 terrorist attacks on the World Trade Center in New York City were considered to be at risk for mesothelioma and other asbestos-related health conditions. Asbestos was used in the construction of the North Tower, and when the building collapsed, hundreds of tons of asbestos were released. Firefighters, police, and volunteers working in the rubble at the site were believed to be at the highest risk. Residents and schoolchildren in the immediate vicinity were also thought to be put at risk.

Symptoms of peritoneal mesothelioma include:

Mesothelioma can also cause blood-clotting * abnormalities or anemia * .

How Do Doctors Diagnose and Treat Mesothelioma?

Diagnosis

Mesothelioma is rare, and misdiagnosis is not unusual because the symptoms are similar to other diseases, including lung cancer. A history of asbestos exposure may suggest mesothelioma. A physical exam or imaging tests can detect fluid in the chest, abdominal cavity, or pericardium.

Other procedures for diagnosing mesothelioma include:

Because it is difficult to distinguish mesothelioma from other cancers by the appearance of the cells, laboratory tests look for markers present on mesothelioma cells.

Biopsies * used to diagnose mesothelioma include:

Staging

Following a diagnosis of mesothelioma, additional imaging tests are performed to stage the cancer and determine if it has spread and, if so, where. Stage I mesothelioma is localized in the lining of the chest wall and possibly the linings of the lungs, diaphragm * , or pericardium around the heart on the same side of the chest.

Advanced mesothelioma is staged as follows:

Treatment

Because mesothelioma is not a single tumor * mass, it is usually not possible to remove it completely by surgery and/or radiation therapy * . If the cancer is localized and the patient is otherwise in good health, curative surgery may be attempted. Extrapleural pneumonectomy removes one lung, the diaphragm, part of the chest lining, and the pericardium. The diaphragm and pericardium are reconstructed with prosthetic material. However, the cancer cells tend to spread and are difficult to detect. Thus, surgery may extend life but is unlikely to cure mesothelioma.

* surgery may be performed to relieve symptoms and control pain:

Radiation therapy is sometimes used as the primary treatment, as an adjuvant (a support) to surgery, or as palliative treatment. Chemotherapy * for mesothelioma is palliative and is usually administered intravenously or directly into the chest or abdominal cavity.

Prognosis

Mesothelioma is usually not diagnosed until the cancer is quite advanced. The average survival time at diagnosis is one year for approximately 40 percent of cases. The five-year survival rate is about 10 percent, which is significantly higher than in earlier decades. Most patients die of complications related to mesothelioma, such as lung failure, heart problems, or stroke * .

Can Mesothelioma Be Prevented?

Although not all mesotheliomas have been connected to asbestos, avoiding such exposure is clearly the best prevention. Precautionary measures should be taken in performing any work that may involve asbestos exposure, particularly demolition of old buildings. It is often more dangerous to remove asbestos-containing materials than to leave them in place. If they are removed, the work should be performed by a qualified contractor.

See also Cancer: Overview • Environmental Diseases: Overview

Resources

Books and Articles

Dockrill, Peter. “New Treatment Can Stop Tumors from Asbestos in Up to 3 Out of 4 Cases.” ScienceAlert. August 13, 2015. http://www.sciencealert.com/new-treatment-can-stop-tumours-from-asbestos-inup-to-3-out-of-4-cases (accessed November 18, 2015).

Maynard, Christopher. “Researchers Find That Aspirin Can Be Effective at Fighting Mesothelioma.” ConsumersAffairs.com . July 7, 2015. http://www.consumeraffairs.com/news/researchers-find-that-aspirincan-be-effective-at-fighting-mesothelioma-070715.html (accessed November 18, 2015).

Pass, Harvey I., Mary Hesdorffer, Sarah Elizabeth Lake, and Sarah Ann Lake. 100 Questions & Answers about Mesothelioma, Third Edition. Sudbury, MA: Jones and Bartlett, 2012.

Websites

MedlinePlus. “Mesothelioma.” U.S. National Library of Medicine, National Institutes of Health. https://www.nlm.nih.gov/medlineplus/mesothelioma.html (accessed October 27, 2015).

Mesothelioma Cancer Alliance. “Mesothelioma.” http://www.mesothelioma.com (accessed May 12, 2016).

The Mesothelioma Center. “Mesothelioma.” http://www.asbestos.com (accessed May 12, 2016).

National Cancer Institute. “Malignant Mesothelioma—Patient Version.” http://www.cancer.gov/types/mesothelioma (accessed May 12, 2016).

Organizations

American Cancer Society. 250 Williams St. NW, Atlanta, GA 30303. Toll-free: 800-227-2345. Website: http://www.cancer.org (accessed October 27, 2015).

Mesothelioma Applied Research Foundation. 1317 King St., Alexandria, VA 22314. Toll-free: 877-363-6376. Website: http://www.curemeso.org/site/c.duIWJfNQKiL8G/b.8598593/k.D685/Homepage.htm (accessed October 27, 2015).

National Cancer Institute. BG 9609 MSC 9760, 9609 Medical Center Dr., Bethesda, MD 20892. Toll-free: 800-422-6237. Website: http://www.cancer.gov (accessed October 29, 2015).

The National Institute for Occupational Safety and Health. Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA 30329. Toll-free: 800-232-4636. Website: http://www.cdc.gov/niosh (accessed November 18, 2015).

* malignant (ma-LIG-nant) refers to a condition that is severe and progressively worsening.

* cancer is a condition characterized by abnormal overgrowth of certain cells, which may be fatal.

* mesothelium (me-zo-THEE-leum) is epithelium derived from embryonic mesoderm that lines the body cavities.

* membrane (MEM-brain) is a thin layer of tissue that covers a surface, lines a cavity, or divides a space or organ.

* peritoneum is the membrane that lines the abdominal cavity.

* abdomen (AB-do-men), commonly called the belly, is the portion of the body between the thorax (THOR-aks) and the pelvis.

* testicles (TES-tih-kulz) are the paired male reproductive glands that produce sperm.

* genetic (juh-NEH-tik) refers to heredity and the ways in which genes control the development and maintenance of organisms.

* susceptibility (su-sep-ti-BIL-i-tee) means having less resistance to and higher risk for infection or disease.

* virus (VY-rus) is a tiny infectious agent that can cause infectious diseases. A virus can only reproduce within the cells it infects.

* incidence means rate of occurrence.

* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.

* DNA or deoxyribonucleic acid (dee-OX-see-ry-bo-nyoo-klay-ik AH-sid) is the specialized chemical substance that contains the genetic code necessary to build and maintain the structures and functions of living organisms.

* clotting is the process by which the body forms a thickened mass of blood cells and protein to stop bleeding.

* anemia (uh-NEE-me-uh) is a blood condition in which there is a decreased hemoglobin in the blood and, usually, fewer than normal numbers of red blood cells.

* trachea (TRAY-kee-uh), also called the windpipe, is the firm, tubular structure that carries air from the throat to the lungs.

* biopsies (BI-op-seez) are tests in which small samples of skin or other body tissue are removed and examined for signs of disease.

* aspiration (as-puh-RAY-shun) is the sucking of fluid or other material out of the body, such as the removal of a sample of joint fluid through a needle inserted into the joint.

* diaphragm (DY-a-fram) is the muscle that separates the chest and abdominal cavities. It is the chief muscle used in breathing.

* lymph nodes (LIMF) are small, bean-shaped masses of tissue containing immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.

* tumor (TOO-mor) is an abnormal growth of body tissue that has no known cause or physiologic purpose. A tumor may or may not be cancerous.

* radiation therapy is a treatment that uses high-energy radiation from x-rays and other sources to kill cancer cells and shrink cancerous growths.

* palliative (PAL-ee-at-iv) means to ease or relieve without curing.

* chemotherapy (KEE-mo-THER-apee) is the treatment of cancer with powerful drugs that kill cancer cells.

* stroke is a brain-damaging event usually caused by interference with blood flow to the brain. A stroke may occur when a blood vessel supplying the brain becomes clogged or bursts, depriving brain tissue of oxygen. As a result, nerve cells in the affected area of the brain, and the specific body parts they control, do not properly function.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)