Asbestos-Related Lung Cancer

Lung cancer is the leading cause of cancer death in the United States, killing 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, and 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, so 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 can reveal the presence of cancer cells.

To make a definitive diagnosis of cancer, however, a pathologist usually has to examine a sample of suspicious tissue under a microscope. The biopsy sample may be extracted through a long needle or with a special tool called a bronchoscope that is passed down the throat and into the airways of the lungs. Occasionally, lung cancer can also be diagnosed by a cytological evaluation of a patient’s sputum.

How Does Asbestos Cause Lung Cancer?

When a person inhales asbestos, microscopic fibers of the toxic mineral can become permanently lodged in the person’s lung tissue. Over many years, these fibers may cause enough irritation and cellular damage to generate cancer cells that grow into a tumor.

Whether someone develops lung cancer or any other asbestos-related disease depends on their overall health, genetics 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 between15 and 35 years to develop. The extraordinarily long latency periods depends on the level of exposure to asbestos and whether the lungs are affected by additional carcinogens such as those commonly found in cigarette smoke.

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, and 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 and banned completely in most developed nations.

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, with the most at-risk professions involving mining, construction, heavy industry, shipbuilding and firefighting.

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

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 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 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 can appear in any part of the lung, and 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, rapidly spreading 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.

How Do Doctors Link Lung Cancer to Asbestos?

The Helsinki Criteria were established in 1997 to 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: