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.
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.
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.
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.