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Exercise May Reduce Lung Cancer Risk for Smokers

A new study finds that physical activity may reduce the risk of lung cancer in current and former smokers. However, smokers still have a much greater risk for lung cancer, regardless of their activity level, than people who’ve never smoked.

Cigarette smoking causes 87% of lung cancer deaths and is responsible for most cancers of the larynx, oral cavity and pharynx, esophagus and bladder, according to NIH’s National Cancer Institute (NCI). A group of researchers from the Universities of Minnesota and Pennsylvania, with funding from NCI, set out to investigate whether lifestyle factors other than smoking could influence the risk of lung cancer.

Women from Iowa were mailed a questionnaire in 1986 about their physical activity, smoking, body mass index and other life-style factors. Almost 37,000 women who had never had cancer were followed through 2002 to record any cancers that developed.

The researchers published their analysis in the December 2006 issue of Cancer Epidemiology Biomarkers & Prevention. There were 777 lung cancers recorded in the study. After adjusting for various factors, the researchers found that women with a high level of physical activity were 23% less likely to be diagnosed with lung cancer than women with a low physical activity level. Those who did a moderate activity more than once a week were 21% less likely to develop lung cancer than women who never did moderate activity. Those who did vigorous activity more than once a week were 29% less likely to develop lung cancer than those who rarely or never did.

While physical activity seemed to reduce the risk of lung cancer in women, its effect was still dwarfed by the effect of smoking. The risk of lung cancer was several times higher in smokers, regardless of activity level, than in those who never smoked.

“The most important thing a smoker can do to reduce risk is to quit smoking,” lead author Dr. Kathryn H. Schmitz of the University of Pennsylvania said. “That said, exercising and being active can offer a marginal change in risk.”