Unlike many other cancers, doctors understand many of the causes of mesothelioma. If you have symptoms that might point to mesothelioma, one of the first questions your doctor might ask is about asbestos exposure. They may also ask about family history, including whether you've had relatives diagnosed with mesothelioma.
Understanding your personal history with known mesothelioma causes helps doctors make more accurate diagnoses. Lung specialists at Penn Medicine's Mesothelioma Program have deep knowledge of mesothelioma risk factors and prevention. We provide individualized care and advanced treatments.
What Causes Mesothelioma?
Most people who develop mesothelioma were exposed to high levels of asbestos at some point in their lives. You may have had a high level of exposure for just a few months (for example, working a summer construction job) or more long-term, low-level exposure from:
- Your workplace or environment
- A contaminated building
- Washing the clothes of someone who worked with asbestos
Asbestos, a mineral found in nature, was commonly used as insulation in construction, shipbuilding, and automotive products for much of the 20th century. When asbestos is disturbed, tiny particles are released into the air and can be breathed in or swallowed. This is called asbestos exposure.
Because asbestos is found in water, air, and soil, everyone is exposed at some point. Most people do not develop cancer from this kind of low-level exposure. People who work in industries where asbestos is common are more likely to be exposed to levels that can be harmful. These industries include:
- Automotive
- Construction
- Military
- Mining
- Shipbuilding
- Other manufacturing industries
These workers can also carry asbestos fibers home on their clothes, which may expose anyone living with them.
Asbestos is no longer mined in the U.S., but asbestos mines still exist here. People who live close to those mines have a higher risk of developing lung cancer, asbestosis, or mesothelioma due to this exposure.
How Does Asbestos Exposure Cause Mesothelioma?
Asbestos fibers are inhaled or swallowed. They then travel to the lining of the lungs (pleura), abdomen (peritoneum), or heart (pericardium) where they irritate and inflame the cells in the mesothelium. This irritation creates scar tissue on the surface of the mesothelium, which can progress to cancer.
Malignant mesothelioma tumors form in that scar tissue, anywhere from 20 to 50 years after asbestos exposure.
Different types of mesothelioma result from different types of asbestos exposure:
- Pleural mesothelioma develops when asbestos fibers are inhaled and stick in the protective lining of the lungs (pleura). Over time, asbestos fibers cause inflammation and scarring within the lining, leading to progression of the disease.
- Peritoneal mesothelioma can form in the peritoneal (abdominal) lining if asbestos fibers are swallowed.
- Pericardial mesothelioma develops in the pericardium (lining of the heart). This type usually starts as pleural mesothelioma that has spread and invaded the pericardium.
Mesothelioma Risk Factors
The most common risk factor for mesothelioma is asbestos exposure. Other factors can increase risk but are less common. Having one or more mesothelioma risk factors doesn't mean you will get cancer—it simply means your risk is elevated.
The risk factors for mesothelioma include:
- Primary asbestos exposure: Primary exposure is direct physical exposure to asbestos fibers. Up to 80 percent of all mesothelioma cases result from primary exposure.
- Secondary asbestos exposure: People who work with asbestos can transfer asbestos fibers from their skin or clothing to other people.
- Radiation exposure: Some research has shown a rare link between radiation therapy for other cancers and increased risk of mesothelioma, with or without asbestos exposure.
- Genetics: In rare cases, family history of mesothelioma is linked to gene mutations, including the BAP1 germline mutation. These genetic changes can increase risk of developing the disease even without asbestos exposure. They also make it more likely that people exposed to even low levels of asbestos will develop mesothelioma.
Understanding your risk factors is important for accurate mesothelioma diagnosis and staging. Mesothelioma specialists at Penn Medicine participate in the Tobacco and Environmental Carcinogenesis Program, a national research group studying environmental exposures and cancer, with a focus on the prevention of asbestos-related cancers like mesothelioma. Our ongoing research helps us better care for people with an elevated risk of mesothelioma, as well as those who already have the disease.
Mesothelioma Prevention
There is no safe level of asbestos exposure—any amount increases your risk of developing mesothelioma. The best way to prevent mesothelioma is to be aware of the presence of asbestos and stay away from it. If you have any risk of exposure, always use protective gear and take safety precautions designed for handling asbestos.
If you suspect your home contains asbestos, contact a trained asbestos mitigation expert. It's not always necessary to remove asbestos from a house just because it's there. The fibers won't get into the air if the material isn't disturbed or damaged.
If you choose to remove household asbestos, or plan to do renovation that may disturb asbestos-containing materials, hire a certified expert who will remove it without causing any exposure.
Genetic Testing for BAP1 Tumor Predisposition Syndrome
About 12 percent of mesotheliomas occur in people who have genetic changes, such as BAP1 tumor predisposition syndrome. This inherited disorder is caused by changes in the BAP1 gene that increase risk of developing mesothelioma and other cancers.
If you have multiple family members diagnosed with mesothelioma or with ocular melanoma (melanoma in the eye, a rare cancer also associated with BAP1 syndrome), you might consider genetic testing. A blood test can detect possible BAP1 gene mutations that increase mesothelioma risk.
At Penn, we provide genetic testing and counseling for people with mesothelioma and other asbestos-related diseases and their families. Understanding your individual risk factors helps us make the most accurate diagnosis and recommend the right mesothelioma treatment and clinical trials for you.
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