Exercise may reduce smokers’ lung cancer risk
Women who smoke may be able to reduce their lung cancer risk with exercise, a new study shows. But the investigators caution that any relative benefit is dwarfed by the benefits gained from kicking the habit.
In the study, women who reported high levels of physical activity were 23 percent less likely to develop lung cancer than those who were the least active, report Dr. Kathryn H. Schmitz of the University of Pennsylvania in Philadelphia and colleagues. And among women who smoked, greater activity was tied to a 28 percent lower lung cancer risk, while women who were ex-smokers showed a 37 percent lower risk with more activity.
Nevertheless, smokers remained at much higher risk of lung cancer than those who had never smoked, or those who had quit, Schmitz and her team note. “Quitting smoking is the single most important action a smoker can take to reduce risk of lung cancer,” they note.
Studies investigating the effect of exercise on lung cancer risk have had mixed results. To better understand the relationship, they looked at 36,929 women participating in the Iowa Women’s Health Study who were followed from 1986 to 2002. Those who reported participating in vigorous activity at least twice a week, or moderate activity more than four times weekly, were classified as having a high physical activity level.
Overall, the researchers found, women who were the most active were 23 percent less likely to develop lung cancer, while those who were moderately active (meaning they exercised vigorously once a week or moderately one to four times weekly) had a 21 percent lower risk than those who were the least active. Women who reported vigorous physical activity more than once a week reduced their lung cancer risk by 29 percent.
Exercise also reduced lung cancer risk among smokers, but had the strongest effect for ex-smokers, the researchers found.
While exercise could be helpful to smokers who aren’t yet willing to quit, and could also be beneficial to women who fear that they will gain weight when they quit, kicking the habit remains “unarguably the most important action for the reduction of lung cancer risk,” the researchers conclude.
SOURCE: Cancer Epidemiology Biomarkers & Prevention, December 2006.
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