Non-Small Cell Lung Cancer - Risk Factors

Risk Factors

Before cigarettes became popular in the beginning of the 20th century, lung cancer was rare. It now strikes roughly 219,000 Americans per year, and about 160,000 die from it annually. The disease usually occurs in people over 50 years old. Men have a significantly greater incidence of lung cancer compared to women. On the encouraging side, the rate of lung cancer in men has been declining significantly over the past decade. While lung cancer rates have been increasing dramatically in women (by 600% from 1950 to 2000), they now appear to be stabilizing. However, lung cancer deaths among female nonsmokers seem to be on the rise.

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Smokers and Those Exposed to Cigarette Smoke

Smoking is the primary risk factor in 85 - 90% of lung cancers. The risk of lung cancer in smokers is about 20 times that of nonsmokers. The risk depends on the duration of the addiction and the number of pack years. (One pack year equals the number of packs of cigarettes smoked per day, multiplied by the number of years that the person has smoked.) Genetic damage in the lung occurs in nearly all chronic smokers, even if cancer has not developed.

People who smoked can be at increased risk for lung cancer more than 20 years after quitting, although the risk drops significantly even in the first year after quitting. There are benefits to quitting smoking, even for people who are well into middle age. Evidence suggests that quitting smoking, after a diagnosis of early stage lung cancer, improves outcomes significantly.

Secondhand Smoke. The Environmental Protection Agency has classified secondhand smoke as a carcinogen (cancer-causing chemical). Exposure to secondhand tobacco smoke increases the risk of lung cancer in the nonsmoker by about 20 - 30%. A 2006 Surgeon General report found that about 3,000 nonsmokers die each year of lung cancer resulting from exposure to secondhand smoke.

Ethnic Differences

There may be some ethnic differences in lung cancer risk. For example, African-American men have about a 45% higher risk of developing lung cancer than Caucasian men. It is not clear what factors are responsible for this higher risk. Some African Americans appear to have a genetic vulnerability to the harmful chemicals in cigarette smoke.

In China, about one-third of all young male smokers will eventually die because of tobacco-related illnesses. Their risk for lung cancer, however, is much less than it is for chronic lung disease, the opposite of the Western trend. The lower rate of lung cancer among Chinese people might be due to a slow rate of clearing nicotine, which results in smoking fewer cigarettes.