Mesothelioma is a rare but serious cancer that affects the tissue that lines the chest and abdomen. While it is not specifically lung cancer, it can occur in the lining around the lungs.1,2
The lining in the inside of the chest, abdomen, and the space around the heart is called the mesothelium. It is made up of cells called mesothelial cells. The mesothelium protects the organs and creates a fluid that lubricates the organs, allowing them to move against each other, such as when the heart beats or the lungs inflate during inhalation. The mesothelium is called by additional names depending on its location in the body:
Around the lungs, it is called the pleura.
In the abdomen, it is called the peritoneum.
Around the heart, it is called the pericardium.1
Cancer begins at the cellular level and can happen in any cell type. When the mesothelial cells become cancerous, the cancer is called malignant mesothelioma.1
Risk Factors for Developing Mesothelioma
The major risk factor for developing mesothelioma is exposure to asbestos over a period of time. Malignant mesothelioma may develop 20 years after a person is exposed to asbestos. Asbestos is a group of minerals that is made up of tiny fibers. These fibers can be found naturally in soil and rocks, and in the past, asbestos was used in many products for its heat and fire-resistant properties. Workers at high risk of exposure to asbestos include miners, factory workers, insulation manufacturers and installers, people who work on the railroad, automotive workers, ship builders, plumbers, and construction workers. If asbestos fibers are inhaled, they can travel through the alveoli (air sacs) in the lungs to the pleural lining, causing scarring and mesothelioma. If asbestos fibers are coughed up and swallowed, they can travel through the stomach into the peritoneum, the mesothelium around the abdomen. Most asbestos exposure happens in the workplace, however family members of people exposed to asbestos at work are also at risk because the asbestos fibers can be carried on the clothes of the workers.1,2
Additional risk factors for developing mesothelioma include increasing age, high doses of radiation to the chest or abdomen, and exposure to zeolites, minerals that are similar to asbestos. Some studies have also found a possible link with an infection of simian virus 40 (SV40). Some polio vaccines from 1955 to 1963 were contaminated with SV40. Mesothelioma is also more common in men, potentially due to the higher likelihood of men being exposed to asbestos in the workplace.1
Symptoms of Mesothelioma
Mesothelioma is most often diagnosed when a person visits a doctor because of their symptoms. Most of the symptoms of mesothelioma can be caused by other conditions, and people may experience symptoms for a few months before diagnosis.
Survival rates are determined on the previous outcomes of people who survive a specific amount of time after diagnosis. In malignant mesothelioma, as in other types of cancer, experts use “5-year survival rate,” or the percentage of people who survive at least five years after diagnosis, as a marker for prognosis (projected outcome). It is important to remember that some patients live beyond this 5-year marker after diagnosis of mesothelioma and these statistics do not necessarily predict what will happen for any particular individual. The relative 5-year survival rate for patients with mesothelioma is between 5% and 10%.1
Written by: Emily Downward | Last reviewed: January 2017.
American Cancer Society. Accessed online on 8/8/16 at http://www.cancer.org/.
National Cancer Institute. Accessed online on 8/8/16 at http://www.cancer.gov/.