Asbestos Lung Cancer
Lung cancer is one of the most common cancers, and researchers estimate about 3 – 4% of all cases can be attributed to asbestos exposure.
Asbestos lung cancer is often misdiagnosed as mesothelioma.
Those with asbestos lung cancer may not experience symptoms for decades.
Smoking increases the risk of developing asbestos lung cancer.
There are an estimated 2,000 – 3,000 lung cancer deaths related to asbestos each year.
Lung cancer is the second most common cancer worldwide and accounted for 1.8 million deaths in 2018. While smoking is the leading cause of lung cancer, it’s estimated that each year between 2,000 and 3,000 of all lung cancer deaths are related to asbestos exposure.
Asbestos-related lung cancer develops after asbestos fibers are inhaled and become embedded in the lung tissue. Smoking, coupled with asbestos exposure, creates an even greater risk of developing the cancer. Exposure to asbestos may cause non-small cell lung cancer (NSCLC) or small cell lung cancer (SCLC).
Asbestos and Lung Cancer
In general, research has shown lung cancer typically develops as a result of toxic exposure, including smoking and radon. Exposure to asbestos is an independent risk factor for the development of lung cancer. The cancer may develop in any individual with exposure to asbestos but is most common in those with prolonged exposure and a history of smoking. The two forms of asbestos-related lung cancer are NSCLC and SCLC.
Between 80 – 85% of all lung cancer diagnoses are NSCLC, and it is also the most common form of asbestos-related lung cancer. NSCLC is the most prevalent asbestos lung cancer among both men and women, as well as smokers and non-smokers.
Types of Non-Small Cell Lung Cancer
- The most common type of NSCLC, occurring in 40% of lung cancer patients.
- Often seen in younger people, women and non-smokers.
- The slow-growing cancer typically forms in the outer part of the lung.
Squamous cell carcinoma
- This type accounts for 25 – 30% of all lung cancer cases.
- Commonly found in patients with a history of smoking.
- Develops in the central part of the lungs.
Large cell carcinoma
- A rarer form of NSCLC, accounting for 10 – 15% of all diagnoses.
- Difficult to treat as it grows and spreads quickly.
- Can develop in any part of the lung.
Small cell lung cancer (SCLC) accounts for 10 – 15% of all lung cancer diagnoses. In most cases, this form is caused by smoking. As such, non-smokers who have been exposed to asbestos are more likely to develop NSLC than SCLC.
Risk Factors of Asbestos-Related Lung Cancer
Asbestos-related lung cancer is caused by exposure to any form of asbestos fiber. Studies have found that lung cancer risk increases with greater exposure to asbestos. The cancer is most common among those handling asbestos on a regular basis, such as those with occupational exposure to the toxin. Some occupations with the greatest risk of asbestos exposure include construction workers, shipyard workers and U.S. Navy veterans.
In most cases, it takes at least 15 years for symptoms of asbestos lung cancer to present. Symptoms of asbestos-related lung cancer are the same as lung cancer caused by other means, which can complicate diagnosis and delay treatment, especially in those with no history of smoking.
Risk Factors Contributing to Asbestos-Related Lung Cancer
- Dose of asbestos
- History of smoking
In addition to the dose of asbestos, the presence of other risk factors compounds the likelihood of developing the cancer. Cigarette smoking coupled with asbestos exposure creates a dramatically increased risk of lung cancer. One study found that asbestos-exposed workers who also had a history of smoking had a 28 times greater chance of dying from lung cancer than those without asbestos exposure. Additionally, the study found that when asbestos-exposed individuals with a smoking history also had asbestosis (scarring of the lung tissue), risk of mortality from lung cancer increased by more than 36 times.
While some risk factors cannot be combatted, such as the amount of asbestos exposure and if asbestosis has developed, smoking history can be altered. Studies have found that 30 years after smoking cessation, the risk of asbestos-lung cancer among previous smokers returns to that of a non-smoker. Quitting smoking is often one of the first things recommended by medical professionals if there’s a known history of asbestos exposure.
Symptoms and Diagnosis of Asbestos Lung Cancer
Asbestos-related lung cancer, like all forms of lung cancer, typically doesn’t become symptomatic until the later stages of the disease.
Symptoms of Asbestos Lung Cancer
- Chest pain
- Coughing up blood
- Difficulty breathing
- Loss of appetite
- Persistent cough
- Repeated cases of pneumonia/bronchitis
- Shortness of breath
- Swelling of the neck/face
- Weight loss
Those who are aware of their previous asbestos exposure should be regularly screened for lung cancer to aid in early detection, diagnosis and treatment. The diagnostic process for lung cancer typically begins with a physical exam, followed by a chest X-ray and lung function tests.
The chest X-ray is the most common test used in the diagnosis of asbestos-related diseases. Since asbestos fibers are microscopic, they cannot be seen on the X-ray. However, the test can alert a patient’s medical team to any early signs of lung disease stemming from previous exposure. If the signs of disease are present, a lung biopsy may be performed. A biopsy is the only way to definitively diagnose a patient with asbestos lung cancer.
Some patients may be ineligible for a lung biopsy if their cancer has advanced and metastasized. Instead, their doctors may recommend the less invasive bronchoscopy. During a bronchoscopy, a thin tube is inserted through the nose or mouth, going down the patient’s throat to examine the trachea, bronchi and lungs. In the case of bronchoscopy for lung cancer diagnoses, an instrument is attached to the end of the tube to extract a tissue sample for testing with a microscope.
The results of the biopsy will enable the doctor to stage the cancer and develop a treatment plan.
Asbestos-Related Lung Cancer Prognosis
The prognosis for asbestos-related diseases, including asbestos-related lung cancer and malignant mesothelioma, is largely impacted by when the disease is diagnosed and how quickly treatment begins.
According to Surveillance, Epidemiology, and End Results (SEER) data from 2008 – 2014, the percentage of patients that achieved 5-year survival increases with earlier diagnosis:
- Overall, 23% of patients diagnosed with NSCLC achieve 5-year survival.
- 60% of patients diagnosed when the cancer was still localized to the lung achieved 5-year survival.
- 6% of those whose cancer had metastasized and was distant from where it originated reached the 5-year survival mark.
Prognosis for SCLC Patients
The overall survival rates for SCLC patients are typically poorer than survival rates for patients with NSCLC because of the speed at which SCLC grows and spreads within the body.
According to the same SEER results, spanning 2008 – 2014, SCLC patients achieved an overall 5-year survival rate of 6%. The percentage of patients that reached the 5-year survival mark again diminishes as the cancer progresses from localized to regional and then distant metastasis.
- Almost 30% of patients diagnosed when the cancer was still localized achieved 5-year survival.
- Comparatively, 3% of patients diagnosed with distant SCLC were alive five years following their diagnosis.
Every patient’s case varies and their medical team can give them the best approximation of their prognosis according to the stage of disease at diagnosis and treatment plan.
Asbestos Lung Cancer Treatment
Viable treatment options for asbestos-related lung cancer vary patient-to-patient according to which form of lung cancer (non-small cell or small cell lung cancer) they are diagnosed with, the stage of the cancer and their goals for treatment. Similar to pleural mesothelioma cancer, asbestos lung cancer is often treated with a multimodality approach, meaning multiple forms of treatment are used.
When diagnosed in the early stages of disease, NSCLC is most commonly treated with surgery. Patients in good overall health may have video-assisted thoracoscopic surgery (VATS) to resect the lobe or portion of the lung containing the lung cancer tumors.
Often, once such surgery is completed, adjuvant therapies (additional therapy to increase efficacy of other treatments) will be used to deter relapse by killing any remaining cancer cells. Adjuvant therapies typically include either radiation or chemotherapy. However, other emerging targeted treatment types may be used, such as immunotherapy and cancer vaccines.
Nivolumab, an immunotherapy drug approved by the Food and Drug Administration (FDA) for the treatment of NSCLC, has been shown to be successful in improving patient survival rates. In one clinical trial, metastatic NSCLC patients treated with Nivolumab as a second-line therapy had a median overall survival of more than one year (12.2 months). Comparatively, those in the trial treated with Docetaxel, a chemotherapy drug, had only a 9.4-month median overall survival. This trial and others with similarly increased survival rates imply that Nivolumab is a promising treatment option for NSCLC patients.
Patients with small-cell lung cancer may have more limited treatment options due to the advanced nature of the cancer. These patients most often receive chemotherapy and palliative treatment for symptom management.
As early detection methods and treatment options continue to evolve, prognosis for patients is anticipated to improve. Those who are aware of previous asbestos exposure should discuss their risks of developing asbestos-related diseases with a medical professional and receive regular check-ups to ensure any irregularities are promptly addressed.