Asbestos-Related Lung Cancer

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.

Medical researchers first made a probable causal relationship between asbestos exposure and lung cancer in 1935. Seven years later, a member of the National Cancer Institute confirmed asbestos as a cause of lung cancer.

Study after study continued to show the cause-effect relationship of asbestos and lung cancer. In 1986, the Occupational Safety and Health Administration (OSHA) proclaimed lung cancer as the greatest risk for Americans who work with asbestos.

Symptoms and Diagnosis of Asbestos-Related Lung Cancer

Whether lung cancer is associated with asbestos exposure 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 the cancer reaches a late stage of development. It is rare for lung cancer to be diagnosed in an early stage unless a patient is regularly screened. Patients with a history of asbestos exposure should seek regular screening for asbestos-related diseases.

The diagnostic process begins with imaging scans such as X-rays and CT scans. If the patient is coughing up sputum, which is a mixture of saliva and mucus, a sputum cytology test might reveal the presence of cancer cells.

A pathologist must examine a sample of suspicious tissue under a microscope to confirm a lung cancer diagnosis. The biopsy sample may be extracted through a long needle or with a special tool called a bronchoscope. A bronchoscope is passed down the throat and into the airways of the lungs.

Lung Cancer Treatment

Treatment options include surgery, chemotherapy, radiation therapy and immunotherapy. Experimental treatments are available through clinical trials. A patient’s treatment plan is determined by the stage and histological type of the cancer. The patient’s overall health also plays role.

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How Does Asbestos Cause Lung Cancer?

When a person inhales asbestos, microscopic fibers of the toxic mineral can become lodged in their lung tissue. Over many years, these fibers may cause enough genetic and cellular damage to cause lung cells to turn cancerous.

Whether someone develops lung cancer depends on several factors. These factors include overall health, genetics, smoking history and the duration and intensity of the asbestos exposure.

All asbestos-related diseases have a long latency period from the time of initial exposure to the onset of symptoms. Asbestos-related lung cancer typically takes between 15 and 35 years to develop. The latency period depends on the level of exposure to asbestos. It also depends on whether the lungs are affected by additional carcinogens such as those commonly found in cigarette smoke.

Mesothelioma Versus Asbestos-Related Lung Cancer

Both diseases take decades to develop but only months to spread or metastasize. The two forms of cancer involve similar diagnostic procedures, but they differ in risk factors, physical characteristics and treatment techniques.

How Are People Exposed to Asbestos?

U.S. companies manufactured a wide variety of asbestos-containing products from the late 1800s up until the 1980s. The mineral was mined at many sites across North America. The mining and commercial use of asbestos is now highly regulated in the United States.

Some chemical, construction and automotive companies still use asbestos. The mineral has not been banned in the U.S.

Because of the long latency period of asbestos-related lung cancer, most cases diagnosed today were caused by asbestos exposure that occurred decades ago before safety regulations existed. Occupational asbestos exposure is the primary cause of asbestos-related disease. The most at-risk professions involve mining, construction, heavy industry, shipbuilding and firefighting.

Veterans are also a high-risk group for asbestos-related lung cancer. This is because of the military’s heavy use of asbestos products in bases, vehicles and ships.

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.

Types of Lung Cancer

There are two primary forms of lung cancer: Small cell and non-small cell. Certain subsets of non-small cell lung cancer (NSCLC) may be less aggressive than the small cell lung cancer variety. Non-small cell lung cancer is definitely a more common malignant disease, accounting for more than 85 percent of all lung cancer cases.

Small cell lung cancer (SCLC) makes up 10-15 percent of cases and is more difficult to treat. In the common clinical cases where small cell lung cancer has spread outside of the confines of the chest, it is almost never a curable disease. Asbestos exposure can cause any one of the various types and subtypes of lung cancer.

Non-Small Cell Lung Cancer

There are three primary subtypes of NSCLC distinguishable by the appearance and chemical makeup of their cells:

Squamous Cell (Epidermoid) Carcinoma

Squamous cell (epidermoid) carcinoma is the most common variety of NSCLC, forming in flat cells that line the inside airways of the lungs. About 25 to 30 percent of all lung cancers are squamous, and this is the most prevalent type of NSCLC among men.

Adenocarcinoma

Adenocarcinoma forms in mucus-producing glandular tissues that line the air sacs (alveoli) of the lungs. It is more common in women than men, and it is the predominant type of cancer among nonsmokers.

Large Cell (Undifferentiated) Carcinoma

Large cell (undifferentiated) carcinoma can appear in any part of the lung. This type grows and spreads more rapidly than the other varieties of NSCLC.

Small Cell Lung Cancer

Typically originating in the bronchi near the center of the chest, SCLC is aggressive and spreads quickly throughout the body. The cancer can disperse from its initial location before presenting any symptoms. It can spread to other parts of the body such as the lymph nodes, bones, liver, adrenal glands or brain.

Unfortunately, surgery is rarely an option with SCLC because of this factor. Doctors instead rely on chemotherapy that attacks cancer cells all throughout the body. In cases where small cell lung cancer is limited to the thorax (chest), chemotherapy and radiation are often used together.

Prognosis and Survival Rates

The prognosis for someone with 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. In the United States, about 18 percent of lung cancer patients survive more than 5 years after diagnosis.

How Do Doctors Link Lung Cancer to Asbestos?

The Helsinki Criteria were established in 1997. They help doctors determine when respiratory diseases are caused by asbestos.

For a lung cancer case to be diagnosed as asbestos related, it must fit two criteria:

Latency Period:

The lung cancer must have developed at least 10 years after the initial exposure to asbestos.

Evidence of Asbestos Exposure:

One of the following must be documented:

• Diagnosis of asbestosis.
• Higher than normal asbestos fibers in lung tissue.
• Exposure to levels of airborne asbestos equal to or greater than 25 fibers per milliliter of air a year (f/mL-yr). To reach this threshold in a one-year work period, the patient must have been exposed to a level of 25 f/mL. Such a high level is typically only found in asbestos manufacturing and asbestos insulation work. To reach 25 f/mL-yr in a five-year period, an individual must have been exposed to asbestos at a level of 5 f/mL. This level is typical of shipbuilding and construction work.

Asbestos-Related Lung Cancer and Asbestosis

The presence of asbestosis is a reliable diagnostic marker that a patient was exposed to asbestos enough to develop lung cancer. Asbestosis and lung cancer are commonly associated. This is because the risk for both rises as asbestos fibers accumulate in lung tissue.

Learn More About Asbestosis

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Karen Selby, RN

Registered Nurse and Patient Advocate

Karen Selby joined Asbestos.com in 2009. She is a registered nurse with a background in oncology and thoracic surgery and was the director of a tissue bank before becoming a Patient Advocate at The Mesothelioma Center. Karen has assisted surgeons with thoracic surgeries such as lung resections, lung transplants, pneumonectomies, pleurectomies and wedge resections. She is also a member of the Academy of Oncology Nurse & Patient Navigators.

Edited by Walter Pacheco

Medical Review By Dr. Don W. Hill