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Mesothelioma is a rare and aggressive cancer that is deadly for most patients. Mesothelioma most often attacks tissue lining the lungs, called the pleura. While the exact cause of any one person’s cancer cannot be known with full certainty, there are several risk factors that can help explain why one person develops mesothelioma and another does not.
The most important risk factor is exposure to asbestos fibers. Being older, male, or working in industries that used asbestos are also known factors. Others include exposure to certain other minerals, exposure to a specific virus, and specific genetic factors.
Causes and Risk Factors
When discussing risk factors for a disease like mesothelioma, it is important to understand the difference between risk factors and causes. A risk factor is something that can be used to determine which populations are more likely to develop mesothelioma. Each risk factor may or may not be a contributing cause. For example, being a man is not a cause of mesothelioma, although men are more likely to develop the disease. Asbestos exposure, on the other hand, is a risk factor but may also be a cause. Tiny asbestos particles in the airways can actually trigger tumor growth.
Asbestos Exposure is the Leading Risk Factor for Mesothelioma
Asbestos exposure is the leading risk factor for mesothelioma. More than any other population, regardless of factors like age and gender, people exposed to asbestos are more likely to develop mesothelioma. Asbestos is also considered a likely cause, although pinpointing the cause of any type of cancer is difficult. Once inhaled, asbestos fibers can lodge in tissues and cause damage, resulting in mesothelioma tumors.
The risk of developing mesothelioma increases when exposed to asbestos early, in large amounts, or for a prolonged period. Although asbestos is a leading risk factor, it cannot be considered a definite cause, and it may not be the only only factor. Only about ten percent of people exposed to asbestos will develop mesothelioma, and not all people who have mesothelioma were ever exposed. Regardless of how strong the connection between asbestos and mesothelioma, there are obviously other contributing factors.
Age, Gender, and Occupation
Other important risk factors for mesothelioma are likely related to asbestos. Being older, being male, and working in certain occupations are all risk factors. Older men are most often diagnosed with mesothelioma, probably because men more commonly work in industries that used asbestos. Age is a factor because mesothelioma takes decades to develop.
Jobs and workplaces that put people at risk for mesothelioma include mining, factories, construction, shipbuilding and repair, automotive repair, and Navy careers. Asbestos was used in many aspects of construction, including insulation, roofing, flooring, plumbing, electricity, and many other applications.
People who worked in construction with these materials, or in factories that manufactured them, were put at risk for developing mesothelioma. Also at risk are people who lived with these workers, as they could transport asbestos fibers on their clothes and skin, resulting in family exposure.
Smoking and General Health with Asbestos Exposure
Mesothelioma is not guaranteed to develop after asbestos exposure. However, there may be other risk factors that increase the odds of developing the cancer. Smoking is a major factor because it is also carcinogenic. Smoking alone is a big risk factor for lung cancer. For those exposed to asbestos, smoking increases the risk of developing this dreadful disease. Other health factors may also contribute, such as being overweight, not exercising, or eating a poor diet.
Other Minerals May Contribute to Mesothelioma
Another group of minerals, called zeolites, have been implicated in mesothelioma. Epidemiological studies of people in a certain region of Turkey have found high rates of mesothelioma, yet no asbestos exposure. What is abundant in the region, are zeolites, including one type of zeolite called erionite. Studies have found that laboratory animals exposed intentionally to the fibers of these minerals develop mesothelioma.
The SV40 Virus
A controversial potential risk factor for mesothelioma is a virus called SV40. This virus, which is found naturally in monkeys, also contaminated a significant proportion of polio vaccines in the the 1950s and 1960s. Thousands of people were exposed to the virus through this vaccine, and there is some research evidence that it could contribute to mesothelioma.
While some experts and most government health officials deny SV40 is a risk factor for mesothelioma, the evidence is compelling. Many studies have found that the virus is present in tumor samples of most patients with mesothelioma. How it may contribute to cancer formation is not understood, but it may be an important risk factor.
Finally, a genetic component may explain why some people develop mesothelioma without ever encountering asbestos. There may be certain genes that increase the risk for developing it. One recently discovered genes was named BAP1. A study of two families with a long history of mesothelioma and other cancers found that these individuals had a mutation in the BAP1 gene. The research also indicates people with this mutation who are also exposed to asbestos are at an even greater risk.
Other gene mutations, including those in CDKN2A and NF2, have been implicated as risk factors for mesothelioma. These, along with BAP1, may play a role in cancer formation because they are tumor suppressor genes. A mutation interferes with the ability of the body to suppress or prevent tumor growth.
Risk factors are like guidelines. They are not causes of mesothelioma and cannot guarantee a person will develop the disease. They simply tell us that certain populations have an increased chance of developing the disease. This is important because it leads to better regulations and advocacy for at-risk people. It is also important because it provides awareness for those with these risk factors. If you have risk factors for mesothelioma, be proactive and receive regular screening to increase the odds of early detection.
Page Edited by Patient Advocate Dave Foster
Dave has been a mesothelioma Patient Advocate for over 10 years. He consistently attends all major national and international mesothelioma meetings. In doing so, he is able to stay on top of the latest treatments, clinical trials, and research results. He also personally meets with mesothelioma patients and their families and connects them with the best medical specialists and legal representatives available.