Lung cancer is the second most common cancer in the United States, with over 200,000 new diagnoses each year. It’s also the leading cause of cancer death each year. Though the largest contributing risk factor for this diagnosis is smoking, studies estimate that about 3 – 4% of lung cancer diagnoses are actually asbestos related.
Asbestos and Lung Cancer
Lung cancer is often associated with some sort of exposure to toxic substances. The vast majority of cases are caused by smoking, but the second leading cause is exposure to radon. Though not nearly as many cases have been linked to asbestos exposure, research has suggested that asbestos-related lung cancer is more prevalent than we realize.
Asbestos exposure often occurs in the workplace, but it can also occur at home as a result of construction projects or deteriorating asbestos products or through secondhand exposure. No amount of asbestos exposure is considered safe, though researchers note that the duration of exposure puts people at a higher lung cancer risk. Once the asbestos is inhaled, our body is unable to remove the toxin and the asbestos fibers can cause damage over time and develop into asbestos cancer.
Many people confuse mesothelioma and lung cancer, since the majority of mesothelioma cases affect the lungs. But malignant mesothelioma develops when the asbestos fibers scar and lead to tumors in the lining of the lungs, the mesothelium. Mesothelioma can also first develop in other parts of the body, like the abdominal cavity or lining of the heart. In cases of asbestos lung cancer, the fibers become lodged in the lung tissue, which can also cause irritation and scarring over time that can develop into tumors. Asbestos can cause any type and subset of lung cancer, including non-small cell lung cancer and small cell lung cancer.
Diagnosing the Symptoms of Asbestos Lung Cancer
All asbestos cancers and asbestos-related diseases take time to develop. The fibers cause health effects like inflammation and scarring over the course of a decade or longer. Asbestos-related lung cancer in particular has a latency period of 15 – 35 years on average.
When asbestos related, the symptoms that first present for lung cancer are largely the same as other asbestos diseases. Some of the differences between these asbestos cancers and how they may present can be attributed to where and how the tumors form. In mesothelioma, for instance, the tumors often create a sheath-like formation across the pleura and other impacted areas, as the cancer cells are known to grow and spread rather quickly. Lung cancer, however, often sees tumors form in more defined areas of the lung initially, though it is also known to be rather quick to spread and grow in the body.
- Persistent cough
- Chest pain
- Difficulty breathing or shortness of breath
- Coughing up phlegm or sputum (mucus from the trachea and bronchi)
- Weight Loss
Like mesothelioma, lung cancer associated with asbestos exposure may be difficult to detect early because of the long latency period and the often nonspecific symptoms that first show. These difficulties can lead to misdiagnosis, which ultimately delays treatment.
Diagnosis usually starts with an imaging scan, like an X-Ray or CT scan which can show any abnormalities with the lungs. The X-Ray may show any masses or nodules in the lung, while a CT scan may be a next step to have more refined imaging of lesions in the lungs that may not appear in an X-Ray.
After initial scans, your doctor may perform a sputum cytology if applicable, a test that will look at the cells of sputum (mucus from the respiratory tract that usually implies infection or disease). For patients producing and coughing up sputum, the sample may reveal cancerous cells. Some patients who show a fluid build up in the lungs (pleural effusion) may also undergo thoracentesis, which takes a sample of the fluid to test for lung cancer cells.
A biopsy or tissue sample will generally be required to confirm the lung cancer diagnosis. There are a number of procedures your doctor can use to get the sample depending on what part of the lung shows signs of cancer. One of the more common procedures is a bronchoscopy, which can be used for examining tumors or blockages in the larger airways. With this procedure, a tube is passed through the mouth or nose into the windpipe to the bronchi, and smaller instruments can then be used to collect tissue and cell samples.
Once the diagnosis is confirmed, your doctor may run some other tests to determine the stage or extent of the cancer to better develop a treatment plan.
Asbestos-Related Lung Cancer Survival Rates
Lung cancer prognosis and survival rates vary widely depending on the type and stage of diagnosis. According to the National Cancer Institute, about 18% of lung cancer patients survive 5 years or more. Though this statistic isn’t very encouraging, only 9% of mesothelioma patients live 5 years or more after diagnosis.
As with other asbestos-related diseases, early detection is truly the best way to improve prognosis. For many patients, however, this isn’t an option given the nature of how asbestos diseases develop. Next to early diagnosis, treatment is critical for patients to beat the odds. Cancer researchers have noted that advancements in treatment with new methods like immunotherapy have improved survival rates in recent years.
Treating Asbestos Lung Cancer
Treatment for mesothelioma, lung cancer and other asbestos cancers typically rely on a multimodal approach dependent on the stage of disease. Similar to mesothelioma, lung cancer is often treated with a combination of conventional treatments like surgery, chemotherapy and radiation therapy.
For patients diagnosed at with early stage asbestos-related lung cancer, surgery followed by chemotherapy is considered the standard of care. The type of surgery depends on how localized the tumors are. Surgery can range from removing a small section of a lung to the entire lobe of a lung, or even a pneumonectomy which entails the removal of the entire lung. A pneumonectomy or extrapleural pneumonectomy is also a common treatment for pleural mesothelioma.
Doctors have also been able to perform less invasive procedures for lung cancer with technological advancements in recent years. For instance, video-assisted thoracoscopic surgery (VATS) has become more common for eligible patients and allows for a shorter recovery period and less potential complications.
Patients eligible for surgical resection often also undergo chemotherapy and sometimes also radiation therapy. Unfortunately, the majority of patients are diagnosed at a more advanced stage where surgery isn’t an option. In these instances, chemotherapy and radiation are the typical course of treatment. For those at the final stages of disease, these treatment options may be applied palliatively to improve quality of life.
More recently, emerging treatments like immunotherapy have also been approved by the FDA to treat lung cancer since clinical trials proved the treatment to be safe and effective. Since 2015, immunotherapy drugs Opdivo (nivolumab), Keytruda (pembrolizumab) and TECENTRIQ (atezolizumab) have all been FDA approved to treat non-small cell lung cancer. There are still ongoing clinical trials for these and other immunotherapies alone and in combination with other treatments, which hopefully will bring researchers closer to finding a cure.Sources
The Mayo Clinic
National Cancer Institute: Asbestos Exposure and Cancer Risk (http://www.cancer.gov/cancertopics/factsheet/Risk/asbestos)
McCormack V, Peto J, et al. Estimating the asbestos-related lung cancer burden from mesothelioma mortality. British Journal of Cancer. January 2012; 106:575–584. doi:10.1038/bjc.2011.563
National Cancer Institute. Cancer Stat Facts: Lung and Bronchus Cancer.
American Cancer Society. Key Statistics for Lung Cancer. January 2018.