Risk Factors for Mesothelioma

Mesothelioma is a rare type of cancer, but it is also aggressive, spreads quickly, and is deadly for most patients. Mesothelioma is a cancer that most often attacks the 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, seen in many cases of mesothelioma, is being exposed to asbestos fibers. Other risk factors include being older, being male, working in industries that used asbestos, being exposed to certain other minerals, being exposed to a specific virus, and having certain genetic factors.

Causes and Risk Factors

In discussing the risk factors for a disease like mesothelioma, it is important to understand that there is a difference between risk factor and cause. 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 instance, being a man is not a cause of mesothelioma, although men are more likely to have the disease. Asbestos exposure, on the other hand, is a risk factor, but it may also be a cause. Asbestos particles in the airways may be what triggers the growth of a tumor.

Asbestos Exposure is the Leading Risk Factor for Mesothelioma

The leading risk factor for mesothelioma is being exposed to asbestos. More than any other population, regardless of other factors, like age or gender, people who have been exposed to asbestos are more likely than others to develop mesothelioma. Asbestos is also considered a likely cause, although pinpointing the cause of any type of cancer is difficult. The fibers of asbestos that are inhaled into the airways are known to lodge in tissues and cause damage.

The risk of developing mesothelioma increases when exposure to asbestos occurs early, when it is prolonged, and when the exposure is to larger amounts of the mineral. Although asbestos is a leading risk factor, it cannot be considered a definite cause or the only factor. Only about ten percent of people exposed to asbestos will develop mesothelioma, and not all people who have mesothelioma were ever exposed to it. This means that there are other contributing factors, regardless of how strong the connection to asbestos is.

Age, Gender, and Occupation

Other important risk factors for mesothelioma are most likely related to asbestos. Being older, being male, and working in certain occupations or workplaces are all risk factors. Older men are most often diagnosed with mesothelioma, probably because men are more likely to have worked in the industries that used asbestos. Age is a factor because mesothelioma takes decades to develop after the initial exposure to asbestos.

Jobs and workplaces that put people at risk for developing mesothelioma include mining, especially for asbestos, factories, construction, shipbuilding and repair, automotive repair, and Navy careers or service aboard ships. Asbestos was used in many aspects of construction, in insulation, in roofing and flooring, in plumbing and electricity, and many other applications.

People who worked in construction with these materials, in repair work, in factories that manufactured them, and in enclosed spaces with these materials, such as on ships, were put at risk for developing mesothelioma. Also at risk are people who lived with these workers, as they could bring asbestos fibers home on their clothes.

Smoking and General Health with Asbestos Exposure

For people exposed to asbestos, mesothelioma is not guaranteed, but 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, but smoking while also being exposed to asbestos may put people at an even greater risk for developing mesothelioma. 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. It is a virus found naturally in monkeys, and which in the 1950s and 1960s was found to have contaminated a significant proportion of polio vaccines. Thousands of people were exposed to the virus through this vaccine, and there is some research evidence that shows it could contribute to mesothelioma.

While some experts and most government health officials deny that 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.

Genetic Factors

Finally, a genetic component may explain why some people never exposed to asbestos get mesothelioma. There may be certain genes that put people at a greater risk for developing it. One of these genes discovered recently 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 that 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 in being 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 the growth of tumors.

Risk factors are like guidelines. They are not causes of mesothelioma and they cannot guarantee that a person will develop the disease or that those without the risk factors will not. They simply tell us that certain populations of people are at a greater risk of having mesothelioma. 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 who do have the risk factors. If you have risk factors for mesothelioma, be proactive, take care of your health, and be screened early and often for cancer.