Exposure to asbestos has been linked to multiple cancers.
Asbestos exposure is currently the only confirmed cause of mesothelioma cancer.
Exposure to asbestos fibers has also been linked to lung, larynx and ovarian cancers.
Some suggest that asbestos may also cause stomach, pharynx and colorectal cancers.
All forms of asbestos have been classified as carcinogenic to humans by numerous organizations, including the U.S. Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC). When inhaled or ingested, these microscopic asbestos fibers become embedded or lodged in the organs, or linings of the organs, and can develop into cancer or other asbestos-related diseases decades later.
Types of Asbestos Cancers
While asbestos exposure has been connected to numerous forms of cancer and illnesses, not all studies have conclusively linked the exposure with the resulting health condition. Some cancers, such as mesothelioma cancer, are undeniably related to asbestos exposure, while others, like stomach cancer, have a more vague association. The length and amount of exposure and type of asbestos fiber are just a few of the elements that may influence the resulting health conditions.
Asbestos Exposure and Cancer Risk
- Lung cancer
- Ovarian cancer
- Laryngeal cancer
- Stomach cancer
- Pharyngeal cancer
- Colorectal cancer
The most common asbestos cancer is malignant mesothelioma cancer. While a rare cancer, impacting about 3,000 Americans each year, studies have repeatedly confirmed that asbestos exposure causes mesothelioma. The first report of mesothelioma due to asbestos exposure was made in 1960. Since then, the connection between the two has only grown.
There are four kinds of mesothelioma:
- Pleural mesothelioma is the most common and affects the lining of the lungs
- Peritoneal mesothelioma is the second most common and impacts the abdominal cavity
- Pericardial mesothelioma is rare and affects the lining of the heart
- Testicular mesothelioma has only been found in a few cases and impacts the testicles
All types of mesothelioma can be difficult to accurately diagnose because it has a long latency period. Mesothelioma often doesn’t become symptomatic until 10 – 50 years after asbestos exposure. As such, prognosis for mesothelioma is generally poor. However, when caught in the early stages of disease, treatment options tend to be more effective and may extend life expectancy.
Asbestos Lung Cancer
Researchers have found that about 3 – 4% of lung cancer cases are linked to asbestos exposure. According to the most recent IARC monograph on asbestos, exposure to long thin asbestos fibers, like chrysotile asbestos, are most likely to cause asbestos lung cancer. Exposure to these fibers causes an estimated 2,000 – 3,000 asbestos-related lung cancer deaths in the United States each year.
Like with other types of lung cancer, smokers who have been exposed to asbestos face an increased risk of developing asbestos lung cancer. Asbestosis, a chronic lung condition caused by asbestos, can also increase the risk of asbestos lung cancer. One study comparing 2,000 insulators with known asbestos exposure to 54,000 workers without exposure found the risk of dying from asbestos lung cancer increased significantly for smokers and those with asbestosis.
Risk of Dying from Asbestos Lung Cancer
|Non-smokers with Asbestos Exposure||5.2 times greater|
|Smokers with Asbestos Exposure||28 times greater|
|Smokers with Asbestos Exposure and Asbestosis||~37 times greater|
In many instances, asbestos lung cancer may be confused for mesothelioma, as most mesothelioma cases develop in the lungs. While mesothelioma develops in the lining of the lung, asbestos lung cancer occurs after asbestos becomes embedded in the lung tissue. Similarly to mesothelioma, it has a long latency period, often developing 15 years or more after the asbestos exposure occurred.
Symptoms of Mesothelioma vs. Lung Cancer
- Chest pain
- Dyspnea (shortness of breath)
- Pleural effusion
- Weight loss
- Chest pain
- Hemoptysis (coughing blood)
- Weight loss
Ovarian and Laryngeal Cancer
Cancers of the larynx and ovaries as a result of asbestos exposure have been studied less than mesothelioma and lung cancer, but have still been conclusively linked to exposure to the fibers. The IARC analyzed 15 case-controlled studies to determine if there’s a link between asbestos exposure and laryngeal cancer. They found 14 of the 15 studies had an odds ratio greater than one, meaning those with asbestos exposure have a greater chance of developing laryngeal cancer than those without exposure. However, despite the data, there is still controversy around the causal relationship between asbestos exposure and laryngeal cancer.
Studies have also shown that ovarian cancer may be caused solely by exposure to asbestos when there is no other causation or family history. One 2018 study highlighted the case of a 57-year-old woman who worked for years in an asbestos factory and lived nearby. Researchers concluded that her epithelial ovarian cancer was caused by a combination of occupational and environmental asbestos exposure. From this report, and others with similar conclusions, researchers believe further studies would be prudent to increase awareness among women who experienced occupational exposure to the carcinogen. Non-occupational exposure to asbestos has also been linked to ovarian cancer diagnoses. Studies have linked asbestos-contaminated talcum powder to several cases of ovarian cancer and mesothelioma in recent years.
Non-Cancerous Health Conditions Caused by Asbestos
While asbestos is a known carcinogen, exposure to the toxin can also cause other chronic health conditions. While these conditions are not considered curable, doctors may recommend treatments that can manage the symptoms. In some cases, these conditions may be a sign of a larger disease like mesothelioma.
- Asbestosis is a chronic lung condition caused by scarring of the lungs from inhaled asbestos fibers. Asbestosis may be diagnosed through a CT scan and listening to the lungs. Physicians may notice a crackling of the breath when examining a patient. Patients typically do not present with asbestosis symptoms until 20 – 30 years after the asbestos exposure. Patients with asbestosis are at a higher risk of developing mesothelioma or lung cancer.
- Pleural plaques are a more asymptomatic asbestos-related disease and considered benign. The plaques form when collagen is deposited within the pleura and calcifies. Pleural plaques occur in roughly 50% of heavily asbestos exposed individuals. The plaques are not believed to be a risk for malignancy in the future and generally do not require treatment.
- Pleural thickening is often thought of in conjunction with pleural plaques, however the two asbestos-related diseases can occur independently of one another. Pleural thickening causes the pleural space to be closed with the accumulation of scar tissue, which impairs breathing. Pleural thickening is treated palliatively in order to reduce patient pain and discomfort and help prevent progression.
Cancers That May Be Caused by Asbestos Exposure
All the types of cancer with a link to exposure to asbestos and asbestos products are not yet known. However, research has inconclusively associated exposure to the toxin with elevated risks of stomach cancer, pharyngeal cancer and colorectal cancer.
A retrospective study found there was a significantly increased risk of stomach cancer after occupational exposure. The increased risk of stomach cancer following asbestos exposure is compounded if other risk factors are present, including chronic infection, smoking and poor diet.
Asbestos-related pharyngeal cancer occurs when microscopic asbestos fibers are inhaled and become trapped in the throat. A 2013 study including more than 1,000 workers found that the longer participants worked with asbestos, the greater their risk of pharyngeal cancer. The incidence of pharyngeal cancer was greatest in participants who were also heavy smokers and drinkers.
According to the limited research, there is stronger evidence of a connection between asbestos and colon cancer than there is of rectal cancer. Studies have found asbestos fibers within the colons of patients with known asbestos exposure and colon cancer upon completion of a biopsy.
Diagnosing Asbestos Cancers
Diagnosing asbestos-related cancers is hindered by the long latency period between asbestos exposure and presentation of disease. It may take anywhere from 10 years to several decades for symptoms to show.
General Symptoms of Asbestos-Related Diseases
- Chest pain
- Difficulty swallowing
- Loss of appetite
- Shortness of breath
- Weight loss
Many tests and scans may be used during the diagnostic process, but the most commonly used is a chest X-ray. If there are signs of asbestos-related disease on the chest X-ray, a biopsy, will be used to definitely confirm the presence of disease. Regardless of the type of asbestos-related cancer, early detection can allow for treatment while in the early stages of disease. Early intervention can also improve prognosis, especially in the case of mesothelioma cancer.
Treatment for Asbestos Cancer
Once definitively diagnosed with an asbestos-related cancer, treatment will vary according to where the condition develops and how it is expected to progress. Chronic conditions like asbestosis and pleural plaques will be treated palliatively to help reduce symptoms and delay progression. Treatment options like medications and lung function tests are common.
Cancers like mesothelioma and asbestos lung cancer are often treated with a multimodal treatment plan, combining standard options like surgery, chemotherapy and radiation. For mesothelioma, newer treatments like immunotherapy have also become more widely used in treatment plans. Clinical trials may also offer eligible patients with mesothelioma and other types of asbestos cancer access to emerging treatments that have shown success in improving survival.
Those who believe they have experienced asbestos exposure should seek medical advice from their healthcare provider to discuss their potential of developing an asbestos-related disease and monitor for any symptoms. Seeking care early can increase treatment options and improve patient prognosis, regardless of the type of asbestos cancer.