Non-Small Cell Lung Cancer - Risk Factors

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Risk Factors

Before cigarettes became popular in the beginning of the 20th century, lung cancer was considered a rare medical phenomenon. This year, lung cancer is expected to strike up to 171,900 Americans, and about 157,000 are expected to die from it. The disease usually appears in people over 50 years old. Men have a significantly greater incidence of lung cancer compared to women. On the encouraging side, the rate in men has been declining significantly over the past decade. And while, lung cancer and been increasing dramatically in women (by 600% from 1950 to 2000), it now appears to be stabilizing.

Smokers and Those Exposed to Cigarette Smoke

Smoking appears to be the primary risk factor in 85% to 90% of lung cancers. About 15% of all people who smoke develop lung cancer, with the risk varying depending 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.) Chromosomal damage in the lung occurs in nearly all chronic smokers, even if cancer has not developed.

An elevated risk for lung cancer can persist for more than 20 years after quitting smoking, although the risk drops significantly even in the first year after quitting. And, there are benefits to quitting smoking even for people who are well into middle age.

Risk for Lung Cancer by Age 75 According to Quitting Age
Quitting Age	Percentage
30	2%
40	3%
50	6%
60	10%

Second-Hand Smoke. The Environmental Protection Agency has classified second-hand smoke as a carcinogen. A number of studies have suggested that exposure to second-hand tobacco smoke may increase the risk of lung cancer in the nonsmoker by about 25%. Still, other studies suggest that the effects of second-hand smoke on adults may be highly over-estimated. A 2003 study in California on smokers and their spouses, for example, found no significant relationship between second-hand smoke and a higher risk for tobacco-related deaths, heart disease, or lung cancer. (It should be strongly stressed, that harmful effects of parental smoking on children have been fairly well established and no one should smoke.)

Ethnic Differences

There appears to be some ethnic differences in lung cancer risk. For example, African Americans face a risk that is two to four times higher than that in Caucasians, regardless of smoking status. It is not clear what factors are responsible for this higher risk. Some African Americans appear to have a genetic susceptibility to the harmful chemicals in cigarette smoke.