Asbestos Lung Cancer
The National Cancer Institute places lung cancer as the leading cause of death from cancer in the United States. One out of every 4 cancer deaths is attributable to lung cancer. In 2016 alone, the American Cancer Society estimated 158,080 deaths from lung cancer.
Lung cancer typically affects older people, with 1/3 of victims diagnosed at the age of 65 or over. The link between asbestos exposure and lung cancer dates back to 1935 but it wasn’t until 1986 when the Occupational Health and Safety Administration announced the risk for lung cancer was greatest among Americans that worked with asbestos. The long latency period makes lung cancer due to asbestos exposure hard to diagnose in the early stages.
What is Lung Cancer?
Lung cancer is a cancer that starts in the lungs and spreads to other organs. Abnormal cells in the lung mutate and cluster together, all while growing uncontrollably. A tumor then develops from the cluster of infected cells, destroying the surrounding healthy lung tissue. As the cancerous cells grow and multiply, they spread to other organs nearby.
Lung Cancer and Asbestos Exposure
When asbestos fibers become airborne, they are easy to inhale and can become trapped inside the lung. As the fibers work themselves deeper into the tissue of the lungs, the infected areas become inflamed and scarring occurs (fibrosis known as asbestosis). The once normal cells begin to change and cluster together ultimately forming tumors in the lung. As the cancer cells continue to grow and multiply, the surrounding healthy tissue becomes more damaged and the organs cease to function properly. These tumors can also spread to other parts of the body, by way of the bloodstream, or the lymph, which is the natural fluid that surrounds the lung tissue.
The Helsinki Criteria was established to offer more concrete evidence and guidelines that some lung and pleural illnesses are connected to asbestos exposure. The groups’ studies found that the risk of lung cancer in relation to asbestos exposure varies due to the length of exposure, the industry worked, and the type of asbestos used. According to the Helsinki Criteria, the chances of developing lung cancer are doubled under the following conditions:
- One year of heavy exposure, or 5 to 10 years of moderate exposure. Heavy exposure includes working with asbestos contaminated materials such as insulation and asbestos spray, as well as exposure in large chunks, like demolishing a building that contains asbestos. Moderate exposure includes occupations like construction workers and shipbuilders.
- The amount of mixed asbestos fibers one is exposed to: 25 fibers per milliliter per year (amphibole plus chrysotile asbestos fibers).
- A previous asbestosis diagnosis.
- Evidence of retained asbestos fiber levels (2 to 5 million amphibole fibers per gram of dry lung tissue).
- The overall amount of asbestos in the body is greater than 10,000 per gram of dry lung tissue.
The risk of lung cancer is expected to rise between 0.5% and 4% for each year that a person is continually exposed, making the duration that one is exposed to asbestos one of the most important factors in determining lung cancer due to asbestos exposure. Smoking plus asbestos exposure increases the risk of developing lung cancer five or more times than smoking alone.
How is Lung Cancer different that Mesothelioma?
Lung cancer and pleural mesothelioma have many of the same symptoms and both can be caused by asbestos exposure. The difference between the two is the location of where the cancer originates. If asbestos fibers become lodged in the lining of the lungs (known as the pleural lining) then pleural mesothelioma is the result. Asbestos fibers in the lung tissue contribute to the diagnosis of lung cancer.
Types of Lung Cancer
There are three main types of lung cancer: small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC), and carcinoid.
- Small Cell Lung Cancer SCLC - There are two types of SCLC: small cell carcinoma and combined small cell carcinoma. Named for how the cells appear under a microscope, small cell carcinoma is often called “oat-cell” cancer. SCLC is less common than NSCLC affecting only about 10% - 15% of people diagnosed with lung cancer. SCLC tends to spread more quickly and is typically treated with chemotherapy.
- Non-Small Cell Lung Cancer - NSCLC is more common than SCLC; affecting approximately 85% of those who have been diagnosed. There are three different types of NSCLC dependent on where the cancer is located on the lungs:
- Adenocarcinoma – Lung cancer that is found in the outer area of the lung.
- Squamous Cell Carcinoma – Lung cancer found in the middle of the lungs, close to the bronchus.
- Large Cell Carcinoma – Lung cancer that is formed in any part of the lung. This form grows and spreads faster than squamous cell carcinoma and adenocarcinoma.
- Carcinoid – A type of tumor made up of neuroendocrine cells that grow slower than the other types of lung cancers. Carcinoid tumors are extremely rare; making up only about 5% of lung cancers. This type of lung cancer is typically treated with surgery to remove the tumor.
Symptoms and Diagnosis
Compared to other organs in the body, the lungs have very little nerve endings. Tumors growing inside the lung or along the lining may not initially produce symptoms that the victim can actually feel until the cancer is in its later stages. The American Lung Association lists the following as symptoms to a possible lung cancer diagnosis:
- Persistent Cough or a chronic cough (i.e., smoker’s cough)
- Wheezing and shortness of breath
- Persistent chest pain
- Coughing up blood
- Frequent lung infections (ex. bronchitis, pneumonia)
Symptoms of lung cancer are not always centered on breathing and the lungs. Lung cancer initially beings in the lungs, but can easily spread to other areas and organs in the body; causing symptoms to appear in those areas first. These symptoms include:
- Loss of appetite and weight loss
- Bone pain or fractures
- Blood clots
Experiencing any of these symptoms paired with other risk factors such as smoking is cause to see a physician and be examined. A lung cancer diagnosis varies from person to person and is contingent upon symptoms, medical history, and physical examination. The following are common and effective tests used in determining a lung cancer diagnosis, according to the American Lung Association:
- CT Scan
- (Computerized tomography) X-ray-type images create 3-D pictures from different angles. These pictures are then combined to determine where abnormalities are in the body. A CT scan can also measure tumor size and if the tumor has spread to other parts of the body.
- PET Scan (Position emission tomography)
- Typically used to show if the cancer had spread to the lymph nodes or other parts of the body, a PET scan involves the injection of a radioactive sugar into the blood. This sugar is then absorbed into the cancer cells. This allows the cancer cells to be easily spotted due to its radioactivity.
- Bone Scan
- Using the bone to determine if cancer cells are present is an effective diagnosis tool. Similar to a PET scan, a small amount of radioactive substance is injected into the vein. As the substance moves through the veins, it pools into areas of the bone that may be infected with cancer. These pools are also known as “hot spots” and are dark in color.
A biopsy is a common procedure used to remove small pieces of tissue to be examined under a microscope.
- Using a bronchoscope, this flexible tube is inserted into the lungs via the mouth or the nose. Tissue samples can be taken from the lung for observation. A bronchoscopy also allows doctor to see into the lungs to visibly determine if there are tumors.
- Endobronchial Ultrasound
- An ultrasound device is placed on the end of a bronchoscope and inserted down into the trachea. The device uses sound waves to take pictures of lymph nodes or any abnormalities that are in the chest. Samples can be taken via a needle that is inserted into the bronchoscope.
- Endoscopic Esophageal Ultrasound
- An endoscope, with an ultrasound device placed at the end, is inserted into the throat and through the esophagus. This procedure is similar to the endobronchial ultrasound.
- Fine Needle Biopsy
- The use of a long, fine needle to remove cells and examine for cancer.
- Mediastinoscopy and mediastinotomy
- The mediastinum is the area located in between the lungs. In this procedure, the doctor takes a look at samples located in that area.
- Sputum Cytology
- The examination of phlegm to detect cancer cells.
- A build-up of fluid around the lungs could indicate cancer, but it could also indicate something else. A thoracentesis involves the fluid around the lungs to be drained as tested for cancer cells.
- This procedure allows doctors to directly investigate small tumors on the lung or the surrounding lining. After a small incision is made in the chest, a small lighted tube with a video camera on the end is inserted into the space between the lungs and chest wall. Doctors are able to more accurately distinguish tumors and even take out tissue samples to be examined under a microscope.
To determine the most effective treatment after one has been diagnosed with lung cancer, doctors will first determine the stage of the disease. The stages of lung cancer are based upon where the lung cancer cells are, the size of the tumor, and if the cancer has spread to other areas and organs in the body. Along with determining the most effective treatments, knowing the stage of lung cancer is helpful in predicting a prognosis. SCLC and NSCLC are assigned two different types of staging. NSCLC uses the TNM (tumor, lymph nodes, metastasis) classification system and SCLC is a simpler two-tiered system.
- Limited Stage – The cancer is “limited” in where it appears, typically confined to the lung and the lymph nodes.
- Extensive Stage – The cancer has spread to other parts of the body.
- Stage I – The developed cancer is confined to just the lung.
- Stage II and III – The cancer has remained in just one lung, but has spread to lymph nodes and other structures within the chest.
- Stage IV – The cancer has spread to both lungs and to other organs such as the brain, liver, bones, or even the adrenal gland.
While a lung cancer diagnosis is grim, lung cancer patients can be comforted to know that there are many treatment options. Determining which treatment option is best relies largely upon the stage of lung cancer, but scientists and researchers also rely on genomic testing for personalized medicine. Genomic testing analyzes the DNA inside the tumor and looks for genetic mutations. These genetic mutations can point doctors in the right direction when determining which chemotherapy drugs will be most effective. The data collected from genomic testing can also help predict if the cancer will come back – resulting in other treatment options such as surgery or radiation.
Treatment options vary by stage and by diagnosis. Those who are diagnosed with SCLC are categorized in just two stages, so chemotherapy is a common treatment as long as the patient is healthy enough. Early stages of NSCLC; however, are typically curable by surgery and in some cases, might be the only treatment required. A combination of treatments such as chemotherapy after surgery occurs during the more advanced stages of SCLC and NSCLC.
- The procedure in which an entire lobe of the lung is removed. One of the more effective forms of surgery, even when the tumor is very small.
- If an entire lobe of a lung cannot be removed, the surgeon can remove portions of the lung where the cancer is located. This is called a segmentectomy.
- Wedge Resection
- Also done in cases where an entire lobe cannot be removed, the surgeon will remove a “wedge-shaped” part of the lung tissue and its surrounding tumor.
- The removal of the entire lung. This typically happens when the cancer has spread to the other lung, or when the cancer is located too close to the center of the chest.
The following are chemotherapy treatments for lung cancer:
- Carboplatn (Paraplatin) or Cisplatin (Platinol)
- Docetaxel (Docefrez, Taxotere)
- Gemcitabine (Gemzar)
- Nab-paclitaxel (Texol)
- Pemetrexed (Altima)
- Vinorelbine (Navelbine)
Chemotherapy, when effective can kill leftover cancer cells, shrink tumors, or even relieve symptoms. Its versatility allows it to be used at different points during the treatment.
Radiation works by producing high-energy x-rays to the affected areas, thus causing damage to the DNA of the cancerous cells. Radiation is also sometimes used with surgery, to help kill any remaining cells that perhaps surgery could not.
- External Beam Radiation – Concentrated doses of radiation from outside the body are aimed at the lung and surrounding areas.
- Brachytherapy – Radioactive material is directly placed on or near the tumor.
- Intensity Modulation Radiation Therapy – An external approach, this treatment uses radiation beams that are shaped like the tumor to more directly target the cancerous area and not the healthier surrounding cells.
- Stereotactic Radiosurgery – An internal approach. High doses of radiation are accurately placed on the tumor in one-day sessions.
Targeted therapy treatments are developed based upon something new a researcher or a scientist has discovered that could be the key in finding successful treatment. These treatments are the latest drugs and procedures developed; contingent on the findings of a scientist or researcher. Targeted therapy for lung cancer focuses on tumor mutation and growth.
- Epidermal Growth Factor Receptor Inhibitors
- Anaplastic Lymphona Kinase Inhibitors
- Anti-angiogenesis therapy
- Monoclonal Anti-bodies
While surgery, chemotherapy, and radiation therapy are some of the most common lung cancer treatments, other treatments such as immunotherapy and the participation in clinical trials can be just as effective. Immunotherapy treatments focus on strengthening the body’s own immune system, which has weakened due to cancer growth. Using the body’s own immune system to attack and kill cancer cells is a strong alternative that does not have the side effects of chemotherapy or radiation. However, immunotherapy treatments have only been approved to treat NSCLC. Clinical trials are imperative to all cancer treatments because it tests how well new procedures and products work in actual patients. Data collected from clinical trials allows for scientists and researchers to make adjustments and to their new procedures and products so doctors can better prevent, diagnose, and treat a disease. The advancement of modern lung cancer treatments relies heavily on the participation of clinical trials.
Survival rates will vary based upon the stage in which the cancer is diagnosed, and other factors such as general overall heath, smoking, and asbestos exposure. Those who are diagnosed in the earlier stages where the cancer has yet to spread have 55% five-year survival rate. Unfortunately, only 16% of victims are diagnosed at an early stage. Those who are diagnosed in the later stages (i.e., once the cancer has spread to other organs and parts of the body), the five-year survival rate is only 4%. The overall five- year survival rate is approximately 17.7% according to National Cancer Institute, and over half of patients diagnosed with lung cancer only survive one year.
- “Lung Health And Diseases”, The American Lung Association, Approved by Scientific and Medical Editorial Review Panel (November 3, 2016). [Link]
- “Small Cell Lung Cancer Treatment (PDQ ®) – Patient Version,” National Cancer Institute (December 16, 2016). [Link]
- Allen Gibbs, MD; Richard Luther Attanoos, MD; Andrew Churg, MD; Hans Weill, MD, “The ‘Helsinki Criteria’ for Attribution of Lung Cancer to Asbestos Exposure,” Archives of Pathology Lab Medicine – Vol 131 (February 2007), [Link]
- “Lung Cancer – Non-Small Cell: Symptoms and Signs,” American Society of Clinical Oncology. [Link]
- “Genomic Testing,” Memorial Sloan Kettering Cancer Center. [Link]