Known Risk Factors

Risk factors associated with lung cancer, as with other disease processes, can be divided into two groups. Modifiable risk factors are those risk factors that we can control or change. Non-modifiable risk factors are those in which we have no control over or cannot change.

Modifiable risk factors associated with lung cancer include:

Smoking:
Approximately 90% of lung cancers are associated with smoking. The risk of developing lung cancer in smokers is 30 times greater than in non-smokers. To understand how doctors evaluate this risk it is necessary to discuss pack-years or the amount of cigarettes (or other smoked substances such as: cigars, pipes, marijuana or herbal cigarettes) per day for a year. Many smokers report a variable amount of cigarettes consumed during different periods of their lives. This makes honest, detailed information important when giving smoking histories to physicians so that they can best determine relative risks and pack-years. For example, if you started out smoking 1 pack per day and continued for 8 years then increased the amount to 2 packs per day for the next 10 years the total number of pack years is 28.

The risk is modifiable because research has shown that if a person quits smoking their risk for developing cancer is significantly lower than those who continue to smoke. Although former smokers still carry a higher risk than non-smokers, the greater number of years spent non-smoking allows the body time to repair the damage to the lungs and regenerate healthy tissue, thereby decreasing the overall risk for the development of lung cancer.

Second Hand Smoke:
Second hand smoke is the exposure to smoke passively by inhalation from the environment. In spite of national efforts to reduce exposure, The American Cancer Society estimates between 5,000 to 10,000 Americans develop lung cancer per year as a result of second hand smoke. One statistic of interest is the spouses of smokers have a 30% greater risk of developing lung cancer when compared to the spouses of non-smokers.

Radon:
Radon is an odorless, tasteless, invisible, radioactive gas found in the soil and rocks of various parts of the US. While minors carry an elevated risk of exposure, homeowners are also at risk. The Environmental Protection Agency (EPA) can provide information on how to test for radon levels in your home. They can be reached at 1-800-SOS-RADON. Radon releases radiation that when inhaled can lead to lung tissue damage and potentially lung cancer. Radon exposure is the leading cause of lung cancer among non-smokers.

Asbestos:
Exposure to airborne asbestos indoors carries a markedly increased risk for the development of lung cancer as well as other lung diseases. Asbestos is found in materials such as plastics, paper products, brakes and clutches on cars and trucks, insulation, ceiling and floor tiles. When these materials are crushed or broken down, asbestos forms tiny fibers capable of being inhaled that damage the lungs. The EPA has classified asbestos as a known human carcinogen (cancer causing agent).

The risk of developing lung cancer among non-smokers is 2-10 times greater when exposed to asbestos. The risk increases to 90 times for those who smoke.
Asbestos is considered to be non-harmful as long as it is not released into the air. It is possible to assess personal exposure to asbestos by requesting your doctor obtain samples of urine, feces or mucus to test for the presence of asbestos. In addition, a chest X-ray may show signs of lung disease associated with asbestos.

Other modifiable risk factors include:
Exposure to industrial chemicals: arsenic; chloride; chromium; nickel; diesel fuel; coal products; uranium.

Exposure to radiation: either occupational exposure or radiation to the chest for the treatment of cancer.

Air pollution

Diet: diets low in fruits and vegetables carry an increased risk for smokers. Fruits and vegetables appear to have some protective capabilities and aide the body in the fight against cancer.


Non-Modifiable Risk Factors

Age:
Advanced age lowers the body’s natural defenses against disease and lung cancer is no exception. As discussed in the section understanding lung cancer, our body has a natural ability to protect against and destroy abnormal cells. As we age, we have a greater likelihood to have repeated exposure to carcinogens and a decrease in natural protective mechanisms. Lung cancer occurs most often between ages 50-70 years.

Family History:
Current research has not identified a specific gene or genes associated with lung cancer. There is, however, a strong suggestion of a genetic predisposition for the development of lung cancer for people who have a parent or sibling who has been diagnosed with lung cancer and engage in known risk factors such as smoking.

Race:
Research indicates that there is an unexplainable greater incidence of lung cancer occurring in African-American males when compared to Caucasian males. The American Cancer Society reports African American males carry a 40% greater risk for developing lung cancer than Caucasian males, killing more African Americans than any other cancer. In addition, African American women have a higher incidence of lung cancer than all ethnicities in the US. Some explanations, although inconclusive, are socioeconomic backgrounds, increased exposure to air pollutants, increased use of menthol cigarettes, dietary differences with high fat consumption, and possibly a genetic variability.

Sex:
Previously, lung cancer has been described as a disease affecting older men. However, an alarming trend among young women being diagnosed with lung cancer seems to indicate that the numbers of newly diagnosed cases of lung cancer between men and women are beginning to equalize. In fact, evidence would suggest that the number of women diagnosed at earlier ages, with less exposure to risk factors, will soon surpass men. Current research indicates that women may be more susceptible to developing lung cancer due to hormone factors and possibly sex-linked genetic factors.

Previous History of Lung Disease:
For obvious reasons, any previous diagnosis of lung cancer should prompt you to take action to reduce modifiable risk factors. Other lung disorders that place you at risk for lung cancer development include: chronic bronchitis, emphysema, chronic obstructive pulmonary disease (COPD) and/or tuberculosis. These disorders cause damage to lung tissue making you more susceptible to cancer causing agents and reduce the lungs natural protective ability to destroy abnormal cells.

Facts:

• Lung Cancer kills more men each year than prostate cancer.
• Lung Cancer kills more women each year than breast cancer.
• More Americans die each year from lung cancer than from breast, prostate and colorectal cancers combined.
• Between 1960 and 1990 deaths from lung cancer among women increased by more than 400%
• In 2003, only $1,740 was spent on lung cancer research per death compared to:
     $13,649 per breast cancer death
     $10,560 per prostate cancer death
     $4,581 per colorectal cancer death