In a study of more than 36,000 women, researchers observed that smokers can reduce their risk of developing lung cancer by being physically active. However, they strongly caution that any relative benefit is dwarfed by the benefits gained from quitting smoking.
The researchers, from the Universities of Minnesota and Pennsylvania, report in the December issue of Cancer Epidemiology Biomarkers & Prevention that a high level of physical activity in women who smoked reduced their relative risk of developing lung cancer by 72 percent. Moderate activity among smokers was associated with a 65 percent risk reduction, and lower relative risks were also seen in former smokers who had moderate or high activity levels.
While this may sound like welcome news to female smokers who don’t want to quit, the investigators emphasize that the absolute risk of developing lung cancer is still much greater in current and former smokers regardless of activity level.
“The most important thing a smoker can do to reduce risk is to quit smoking. That said, exercising and being active can offer a marginal change in risk,” said the study’s lead author, Kathryn Schmitz, Ph.D. an assistant professor at the University of Pennsylvania. Schmitz worked on the study with a team of researchers while on faculty at the University of Minnesota.
In other words, she says, a physically active smoker has a 35 percent lower risk of lung cancer than a sedentary smoker, but if both smokers quit, they would both reduce their risk by as much as 10- or 11-fold. “Smokers who exercise are at a 35 percent lower risk of developing lung cancer relative to smokers who don’t exercise, but if you smoke at all, your risk of developing lung cancer is 10- to 11- fold higher than if you didn’t smoke.”
“The helpful message from this study is that if a smoker is having trouble quitting, exercise can be a first step toward better health,” says Schmitz.
The findings were derived from the Iowa Women’s Health Study, which in 1986 began to follow almost 42,000 women between the ages of 55 and 69. Over the years, five questionnaires were sent to the participants who recorded their smoking status and physical activity among other variables. This analysis, which began in 2002, included 36,410 participants, including 777 women diagnosed with the cancer. Among this group, 125 were non-smokers, 177 were former smokers, and 475 were current smokers.