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What Should I Know About Lung Cancer Caused by Asbestos?
Only a small percentage of lung cancer cases are primarily linked to asbestos. Tobacco smoking accounts for about 80% of lung cancer deaths in the United States. Exposure to asbestos increases the risk of lung cancer in smokers and non-smokers.
Lung cancer is the leading cause of cancer death in the United States. It kills more Americans each year than breast, prostate and colon cancer combined. Lung cancer caused by asbestos is responsible for an estimated 6,000 deaths in the U.S. each year.
Quick Facts About Asbestos Lung Cancer
- Symptoms include shortness of breath, chest pain and coughing up blood
- May develop 15 to 35 years after asbestos exposure
- Two main forms are small cell and non-small cell
- Prognosis and treatment depend on type and stage of cancer
Mesothelioma vs. Asbestos-Related Lung Cancer
Lung cancer caused by asbestos is different than pleural mesothelioma, an asbestos-related cancer that develops in the lining of the lungs instead of inside the lung. Both diseases take decades to develop but only months to spread or metastasize.
Pleural mesothelioma and asbestos lung cancer involve similar diagnostic procedures and symptoms, but they differ in physical characteristics and treatment techniques. Asbestos exposure is the primary cause of mesothelioma, while smoking is by far the leading cause of lung cancer.
But asbestos exposure causes six times more cases of lung cancer than mesothelioma. Lung cancer claims the most lives of all asbestos-related diseases.
How Does Asbestos Cause Lung Cancer?
When a person inhales asbestos, microscopic fibers can become lodged in their lung tissue. Researchers have been studying just how these asbestos fibers cause cancer and found evidence that asbestos may spark changes within DNA itself.
The International Agency for Research on Cancer is the specialized cancer agency of the World Health Organization. In 2017, IARC conducted an extensive research study that provided new evidence to connect asbestos and a chemical reaction that changes specific genes in the body.
This chemical reaction – DNA methylation – impacts biological processes. IARC researchers explained that “epigenetic mechanisms such as DNA methylation are fundamental in the regulation of gene expression and carcinogenesis.” Carcinogenesis is the beginning of cancer formation.
Significantly impacted biological processes include:
- Potassium ion transport: Potassium channels regulate cancer behaviors and can have anti-tumor effects. An impact on their ability to fight tumors could allow cancer to aggressively progress.
- Neuron differentiation: Regulation of neuron differentiation in cancer can determine if cells are well-differentiated or undifferentiated. Well-differentiated cancer cells spread more slowly while undifferentiated cells can spread more quickly.
While the asbestos can trigger the body’s nervous system to fuel tumor development and spread, the process itself may take decades from the point of exposure until the onset of symptoms. Asbestos-related lung cancer typically takes between 15 and 35 years to develop.
Because of this long latency period, most cases diagnosed today began with occupational asbestos exposure that occurred decades ago. Veterans and others connected with military service are at high risk because asbestos use in the military was extensive. Mining, construction, heavy industry, shipbuilding and firefighting are also high-risk groups.
While not all people exposed to asbestos will develop lung cancer, those exposed to large amounts of asbestos for long periods of time are at the most risk.
Risk factors for asbestos lung cancer include:
- Duration and intensity of asbestos exposure
- Smoking history
- Overall health
According to an international study published in 2020, no substance causes more cases of lung cancer linked to occupation than asbestos. The study found that asbestos is responsible for 37.5% of all occupational lung cancer cases.
Asbestos-Related Lung Cancer and Smoking
The risk of lung cancer is much higher among asbestos-exposed smokers because smoking impairs the lungs’ ability to remove asbestos fibers. Smokers who have been exposed to asbestos should stop smoking immediately and seek annual screenings for lung cancer.
Symptoms and Diagnosis
Whether lung cancer is associated with asbestos exposure, smoking or another cause, it presents the same general symptoms:
- Persistent coughing
- Shortness of breath
- Chest discomfort or pain
- Hoarseness or wheezing
- Coughing up blood
- Fatigue and loss of appetite
- Swelling of the face or neck
- Chronic respiratory infections
These symptoms typically only arise once lung cancer reaches a late stage of development, when the cancer is tougher to treat. People with a history of asbestos exposure should seek regular screening for asbestos-related diseases.
How Is Asbestos Lung Cancer Diagnosed?
The diagnostic process begins with imaging scans such as X-rays and CT scans. A 2021 clinical research study noted that PET-CT scans of patients with asbestos-related lung cancer showed comparable sensitivity and specificity to similar scans of patients with conventional lung cancer.
A pathologist must examine a biopsy sample of suspicious tissue to confirm a lung cancer diagnosis.
A biopsy may be extracted through a long needle or with a bronchoscope, which is passed down the throat and into the airways of the lungs.
Lung Cancer Treatment
Treatment options for asbestos-related lung cancer include surgery, chemotherapy, radiation therapy and immunotherapy.
Aggressive treatments aim to remove or kill cancer cells to prevent the spread of cells and tumors. Palliative therapies help ease pain and other symptoms to improve quality of life.
- Surgery: Tumor-removing surgery may be an option if the cancer is diagnosed in an early stage when spread is limited. Doctors may remove the tumor and a small portion of the lung (wedge resection), one of the lung lobes (lobectomy) or the entire lung (pneumonectomy).
- Chemotherapy: This is the most common treatment when lung cancer has spread from the initial tumor. It aims to shrink tumors and kill cancer cells.
- Radiation Therapy: High-energy targeted radiation is used to kill cancer cells or slow growth.
- Immunotherapy: Several immunotherapies such as pembrolizumab (Keytruda) and nivolumab (Opdivo) have been approved to treat advanced non-small cell lung cancer. Immunotherapies amplify immune response to recognize and kill cancer cells.
Prognosis and Survival Rates
The prognosis for lung cancer depends on the type and subtype of the disease. It also depends on the patient’s overall health and how far the cancer has spread by the time it has been diagnosed (the stage of the cancer).
About 18% of lung cancer patients survive more than five years after diagnosis, according to the American Lung Association. This is significantly lower than other leading cancers such as breast (89.6%) and prostate (98.2%).
More than half of lung cancer patients die within one year of being diagnosed.
Types of Lung Cancer
There are two primary forms of lung cancer: Small cell and non-small cell. Asbestos exposure can cause any of the various types and subtypes of lung cancer.
Non-Small Cell Lung Cancer
Non-small cell lung cancer (NSCLC) accounts for about 85% of all lung cancer cases. There are three subtypes of non-small cell: Squamous cell carcinoma, adenocarcinoma and large cell carcinoma.
- Adenocarcinoma forms in mucus-producing glandular tissues that line the air sacs (alveoli) of the lungs. Accounting for about 40% of all NSCLC cases, adenocarcinoma is the most common type of lung cancer seen in non-smokers.
- Squamous cell (epidermoid) carcinoma forms in flat cells that line the inside airways of the lungs. It accounts for about 25% to 30% of all lung cancers.
- Large cell (undifferentiated) carcinoma can appear in any part of the lung. This subtype grows and spreads more rapidly than the other varieties of NSCLC. About 10% to 15% of all lung cancers are large cell.
Small Cell Lung Cancer
Small cell lung cancer (SCLC) makes up 10% to 15% of cases and is more difficult to treat. The cancer can spread to other parts of the body before presenting any symptoms.
Unfortunately, surgery is rarely an option with SCLC because of this factor. Doctors instead rely on chemotherapy that attacks cancer cells throughout the body.
How Do Doctors Link Lung Cancer to Asbestos?
The Helsinki Criteria were established in 1997. These standards help doctors determine if asbestos is the primary cause of respiratory diseases.
- Latency Period: The lung cancer must have developed at least 10 years after the initial exposure to asbestos.
- Evidence of Asbestos Exposure: This may include a diagnosis of asbestosis, higher than normal asbestos fibers in the lung tissue and exposure levels of airborne asbestos equal to or greater than 25 fibers per milliliter of air a year. This level is typical of shipbuilding and construction work.
Asbestos-Related Lung Cancer and Asbestosis
Asbestosis and lung cancer are commonly associated. This is because the risk for both rises as asbestos fibers accumulate in lung tissue.
The presence of asbestosis is a reliable diagnostic marker that a patient was exposed to asbestos enough to develop lung cancer.
Common Questions About Asbestos-Related Lung Cancer
- What types of lung cancers does asbestos cause?
Asbestos exposure can cause any type of lung cancer. The two broad classifications of lung cancer are non-small cell and small cell, which are subcategorized by cell type. People with a smoking history are more susceptible to asbestos-related lung cancer. Asbestos is also the primary cause of pleural mesothelioma, which forms in the lining outside the lungs and is not considered lung cancer.
- Does everyone exposed to asbestos get lung cancer?
Not every person exposed to asbestos will develop lung cancer or other asbestos-related diseases. A person’s risk of illness will increase relative to their level of exposure to asbestos. Frequent and extended periods of concentrated asbestos exposure present the highest risk.
- What is the difference between mesothelioma and asbestos-related lung cancer?
All forms of lung cancer originate inside the lungs. Mesothelioma is also cancer, but it develops in the tissue that lines the outside of the lungs, chest cavity and abdomen. Asbestos exposure can cause both types of illness.