How Does Asbestos Cause Cancer?
Asbestos is a unique mineral that can be pulled apart into flexible fibers. When a person inhales or swallows microscopic asbestos fibers, their body often cannot degrade or expel them. Over many years, the fibers cause inflammation and genetic changes that can lead to cancer.
Lifestyle factors may increase your risk of developing cancer after asbestos exposure. These include smoking, heavy alcohol use, poor dietary habits and poor physical fitness.
Most cases of asbestos-related disease are linked with occupational exposure. The World Health Organization says asbestos causes half of all occupational cancer deaths. Secondhand and environmental asbestos exposure can cause cancer as well.
Asbestos Exposure Causes Four Types of Cancer:
- Lung cancer
- Laryngeal cancer
- Ovarian cancer
What are the Symptoms of Asbestos Cancer?
People with a history of asbestos exposure should seek regular health screenings. They should pay special attention to the following signs, which may signal cancer:
- Shortness of breath, coughing, chest pain: These are symptoms of pleural mesothelioma, pericardial mesothelioma and lung cancer.
- Abdominal changes: Swelling and pain, digestion issues, changes in bowel habits and nausea are symptoms of peritoneal mesothelioma, stomach cancer, colon cancer and ovarian cancer.
- Reproductive and sexual differences: Menstrual changes, fatigue, back pain and pain during sex can be symptoms of ovarian cancer.
- Throat changes: Persistent hoarseness, feeling the need to clear your throat often and difficulty swallowing can signal laryngeal cancer and pleural mesothelioma.
Diagnosis and Treatment of Asbestos Cancers
Diagnosing an asbestos cancer is a lengthy process. These tumors can be mistaken for other cancers and less serious conditions such as pneumonia or bronchitis.
Steps to Diagnose Asbestos Cancers
- Referral: A primary care physician refers the patient to a specialist depending on which part of the body is affected.
- Imaging tests: X-rays, CT scans, MRIs and PET scans help doctors look inside the body for tumors.
- Blood tests: Blood tests look for other signs of cancer such as abnormal blood cell counts.
- Cancer biopsies: Biopsies are tissue samples collected in and around a tumor. They help determine the type of cancer. Biopsies are used to diagnose mesothelioma, lung cancer and ovarian cancer. A colonoscopy can be used to collect a biopsy to diagnose colon cancer.
- Treatment planning: With chemotherapy, the specific drugs used vary depending on the disease site. Immunotherapy has been approved for lung cancer. It is being tested in clinical trials for other cancers, too.
- Treatment: Doctors treat mesothelioma and other forms of asbestos cancer with surgery, chemotherapy, radiation therapy or multimodal therapy, which a combination of these options.
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Cancers Definitively Linked to Asbestos Exposure
The most recent report from the International Agency for Research on Cancer (IARC) confirms asbestos causes four types of cancer: Mesothelioma and lung, laryngeal and ovarian cancers.
Of these tumor types, asbestos risk is most pronounced for mesothelioma and lung cancer, although all of these diseases are known asbestos cancers.
A 2018 Italian study followed 3,984 shipyard workers for 55 years. The researchers tracked down death certificates for 84% of this group by December 2014.
The investigators produced estimates of “excess” deaths — deaths that wouldn’t have occurred without asbestos exposure — in the group. There were 575 excess deaths due to mesothelioma and 90 from lung cancer.
Doctors first documented the health hazards of asbestos exposure nearly a century ago. Unfortunately, asbestos-industry executives suppressed and manipulated medical research for decades.
These actions have led to many more asbestos exposures than may have occurred if people were informed on how to protect themselves from the mineral decades ago.
Because of the asbestos industry’s negligence, thousands of lawsuits have been filed by mesothelioma lawyers on behalf of cancer patients seeking compensation.
All branches of the U.S. military also used asbestos, and that’s why veterans have an elevated risk of developing mesothelioma or other asbestos cancers.
Mesothelioma is the only type of cancer almost exclusively caused by asbestos exposure.
Around 70% to 75% of mesotheliomas form in the pleura (lining of the lungs). Nearly 20% form in the peritoneum (lining of the abdomen). In very rare cases, cancer develops in the lining around the heart or testes.
A 2017 Centers for Disease Control and Prevention publication indicated 45,221 malignant mesothelioma deaths were reported between 1999 and 2015.
The reported mesothelioma death rate increased from 2,479 in 1999 to 2,597 in 2015. Despite the decreases in known asbestos exposures, cases do not appear to be declining. That CDC report suggests there is ongoing inhalation exposure to asbestos fibers.
Asbestos-related lung cancer kills twice as many Americans each year as mesothelioma. Asbestos exposure is the primary cause of about 4% of lung cancer cases.
Most lung cancer cases trace back to smoking cigarettes. However, the combination of smoking and asbestos exposure greatly increases the risk of developing lung cancer. More than 220,000 lung cancer cases were diagnosed in the U.S. in 2017.
The American Cancer Society estimates there were 526,510 lung cancer survivors — more than half a million — in the U.S. in 2016. That number is expected to increase to 673,370 lung cancer survivors by 2026.
Larynx, or voice box, cancer usually is linked to smoking and excessive alcohol consumption. However, inhaled asbestos fibers also can lodge in the voice box as they are passing through the trachea (windpipe) on the way to the lungs.
More than 13,000 cases of laryngeal cancer occurred in 2017, according to the American Cancer Society. The combination of smoking, heavy drinking and asbestos exposure increases a person’s laryngeal cancer risk significantly.
Ovarian cancer was diagnosed in more than 22,000 American women in 2017. For most cases, a definitive cause is unknown. However, medical research has established asbestos exposure as one cause of ovarian cancer.
Researchers are still debating how exposure to asbestos dust causes ovarian cancer. Some cases have been linked to personal hygiene products made from asbestos-contaminated talcum powder.
Court filings show Imerys, a major talc supplier for Johnson & Johnson, was facing more than 14,000 claims in 2019 from women who alleged asbestos-contaminated talc caused their ovarian cancer.
Cancers ‘Positively Associated’ with Asbestos Exposure
The IARC also identified three types of cancer “positively associated” with asbestos exposure. This means there is some evidence of a link, not strong enough data to conclude asbestos definitively causes these diseases.
Cancers Positively Associated with Asbestos Exposure
- Pharyngeal cancer
- Stomach cancer
- Colon cancer
The pharynx is the membrane-lined cavity behind the nose and mouth, connecting these areas to the esophagus (back of the throat). Pharyngeal cancer develops here.
Air passes through the pharynx on the way to the windpipe, and food and water pass through the area on the way to the esophagus. Inhaled or swallowed asbestos fibers can accumulate in the pharynx.
Pharyngeal cancer afflicted about 17,000 Americans in 2017. Although linked to asbestos exposure, the main risk factors are smoking and excessive alcohol consumption.
About 28,000 Americans developed stomach cancer in 2017. Infection with Helicobacter pylori bacteria, smoking and a diet heavy in salt, cured meats and preservatives are the main risk factors.
A 2019 paper in Advances in Experimental Biology and Medicine details how H. pylori leads to stomach cancer in some people.
Researchers have suggested asbestos-contaminated water may contribute to elevated stomach and other gastrointestinal cancer risk. Industrial pollution or crumbling asbestos-cement pipes may contaminate water.
The IARC report noted a positive association between asbestos exposure and colorectal cancer. The majority of studies have pointed to the colon specifically. There is less evidence linking asbestos to rectal cancer.
Smoking, excessive alcohol consumption, a low-fiber diet and a sedentary lifestyle are important risk factors for colorectal cancer. A diet high in processed and red meats also increases risk.
Cancers with Possible Links to Asbestos Exposure
Asbestos fibers most often lodge in lung tissue and the pleura, which is the lining around the lungs. They also migrate into organs and tissues in other areas of the body.
For this reason, researchers have studied the connection between asbestos and many types of cancer.
Kidney cancer is one of the 10 most common cancers in the U.S. It is linked to heavy metal, herbicide and industrial chemical occupational exposures. Recent studies suggest a potential link to asbestos exposure as well.
Other risk factors include smoking, obesity, certain medications and advanced kidney disease. More than 60,000 Americans were diagnosed with kidney cancer in 2017.
About 17,000 cases of esophageal cancer occurred in the U.S. in 2017. This disease arises in the tube that carries food from the mouth and throat into the stomach.
The main risk factors include smoking, excessive alcohol consumption, obesity and acid reflux disease. Some experts have uncovered a link to asbestos exposure as well.
Breast cancer is the most common cancer diagnosis in the U.S., not including skin cancer. It affected more than 255,000 Americans in 2017.
Breast cancer risk factors include family history, obesity, excessive alcohol consumption, poor physical fitness and certain hormone-based medications and therapies.
Research has not uncovered a significant link between breast cancer and asbestos exposure.
Prostate cancer is one of the most common types of cancer in men, afflicting more than 160,000 Americans in 2017. Little is known about its causes, though family history and older age are the main risk factors identified to date.
A “Western” diet high in fat and low in fiber, vegetables and fruit also may contribute to increased prostate cancer risk.
Research into the link between prostate cancer and asbestos exposure has been inconclusive.
LeukemiaLeukemias are diagnosed in more than 60,000 Americans each year. These cancers develop in the bone marrow and blood. Doctors do not yet have a clear understanding of what causes them.
Although a few case studies have suggested a link between asbestos exposure and leukemia, the medical evidence for this connection is not strong.
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Last Modified June 28, 2019