Exercise Could Reduce Your Cancer Risk

(November 18, 2008) - Exercise is good for more than just your waistline. (Read about "Getting Started on Fitness") A recent study suggests that regular physical activity can lower a woman's overall risk of cancer - but only if she gets a good night's sleep. (Read about "Cancer: What It Is" "Sleep") Otherwise, lack of sleep can undermine exercise's cancer prevention benefits.

"Greater participation in physical activity has consistently been associated with reduced risk of cancer incidence at several sites, including breast and colon cancers," said James McClain, Ph.D., cancer prevention fellow at the National Cancer Institute and lead author of the study. (Read about "Breast Cancer" "Colorectal Cancer") "Short duration sleep appears to have opposing effects of physical activity on several key hormonal and metabolic parameters, which is why we looked at how it affected the exercise/cancer risk relationship."

Even though the exact mechanism of how exercise reduces cancer risk isn't known, researchers believe that physical activity's effects on factors including hormone levels, immune function (Read about "The Immune System") and body weight may play an important role. The study examined the link between exercise and cancer risk, paying special attention to whether or not getting adequate sleep further affected a women's cancer risk.

Almost 6,000 women were studied for close to 10 years. Women in the top 50 percent of physical activity showed significantly reduced risk of overall cancer and breast cancer. However, sleeping less than seven hours a day increased overall cancer risk, negating much of the protective effects of physical activity on cancer risk for this group.