Malignant mesothelioma (me-zoe-thee-lee-O-muh) is a rare but aggressive cancer affecting the thin layer of tissue that covers the majority of your internal organs (mesothelium) especially the membrane lining of the lungs and abdomen.
Malignant mesothelioma is the most serious of all asbestos-related diseases. Exposure to asbestos is the primary cause and risk factor for mesothelioma. Mesothelioma is primarily caused by exposure to asbestos, though cases have been documented in children or other individuals with no asbestos history.
What is Asbestos?
Asbestos is a microscopic and naturally-occurring mineral that lodges in the pleural lining of the lungs and the peritoneal lining of the abdominal cavity. In most cases, several years and even decades may pass before mesothelioma develops in those who have been exposed to asbestos.
The Primary Risk factor for Mesothelioma is Asbestos Exposure
Asbestos is a mineral that’s found naturally in the environment that had a wide variety of useful applications, including insulation, brakes, shingles, flooring and many other products as the asbestos fibers are strong and resistant to heat.
Asbestos dust may be created when asbestos is broken up during the mining process or when removing asbestos insulation. If the dust is inhaled or swallowed, the asbestos fibers will settle in the lungs or in the stomach. These fibers can cause irritation that may lead to mesothelioma. It can take 30 to 40 years or more for mesothelioma to develop after asbestos exposure. Not all people exposed to asbestos develop mesothelioma while others with very brief exposure develop the disease.
Factors that may increase the risk of mesothelioma include:
Personal history of asbestos exposure. Being exposed to asbestos fibers at work or at home, including living with someone who works with asbestos. People who are exposed to asbestos may carry the fibers home on their skin and clothing, exposing the people around them.
Some research indicates a link between mesothelioma and monkey virus used in polio vaccines. The simian virus 40 (SV40), is a virus originally found in monkeys. Between 1955 and 1964, millions of people may have been exposed to SV40 when receiving polio vaccinations because the vaccine was developed using monkey cells. The virus was removed from the polio vaccine once it was discovered that SV40 was linked to certain cancers. The link is still a point of debate, and more research is needed.
Making a correct mesothelioma diagnosis is particularly difficult for doctors because the disease often presents with symptoms that mimic other common ailments.
The Three Major Types of Mesothelioma
Doctors divide mesothelioma into different types based on what part of the mesothelium is affected. Three major types of mesothelioma exist and they are differentiated by the organs primarily affected.
Pleural malignant mesothelioma: Affects the lung’s protective lining in the chest cavity. Pleural malignant mesothelioma represents about three-quarters of all mesothelioma incidence.
Peritoneal mesothelioma: Affects the tissue in abdominal cavity, heart and around the testicles.
Pericardial mesothelioma: Affects the cardiac cavity.
Mesothelioma does not include a form of noncancerous (benign) tumor that occurs in the chest and is sometimes called benign mesothelioma or solitary fibrous tumor.
The mesothelium of the chest, abdomen, and cardiac cavity are called the pleura, the peritoneum, and the pericardium, respectively. Each of these groupings of mesothelial cells is extremely critical to the functions of the body structures which they encompass.
The mesothelium is particularly important to organs that are commonly in motion, such as expansion or contraction of the lungs, stomach, or heart. Lubrication from the mesothelial cells allows free range of motion within the body.
Malignancies (cancerous tumors) occurring within the mesothelial membranes are known as malignant mesothelioma, or simply mesothelioma. Benign tumors of the mesothelium are known to occur, but are much more rare than malignant mesothelial tumors.
While tumors of the mesothelium were first recognized in the late 18th century, it was not until the middle of the 20th century that this particular cancer was studied and examined with more detail. It was at this time when suspicions of the cancer’s causal relationship with asbestos exposure became more substantiated. A joint research venture through the Department of Thoracic Surgery at the University of the Witswater and Johannesburg General Hospital in South Africa provided the most compelling evidence of the nexus between asbestos exposure and the development of pleural mesothelioma.