Parents, here’s another reason to encourage your daughters to go out for sports or just regular brisk walks. In the largest, most detailed analysis to date of the effects of exercise on premenopausal breast cancer, a study of nearly 65,000 women found that those who were physically active had a 23 percent lower risk of breast cancer before menopause. In particular, high levels of physical activity from ages 12 to 22 contributed most strongly to the lower breast cancer risk.
Girls and young women who exercise regularly between the ages of 12 and 35 have a substantially lower risk of breast cancer before menopause compared to those who are less active, the new research concludes.
The study was conducted by researchers at Washington University School of Medicine in St. Louis and Harvard University in Boston. According to lead investigator, Graham Colditz, M.D., Dr. P.H.: “We don’t have a lot of prevention strategies for premenopausal breast cancer, but our findings clearly show that physical activity during adolescence and young adulthood can pay off in the long run by reducing a woman’s risk of early breast cancer.”
One-fourth of all breast cancers are diagnosed in women before menopause. Numerous studies have shown that physical activity reduces the risk of postmenopausal breast cancer, but the few studies that have looked at the influence of exercise on breast cancer risk before menopause have produced conflicting results, so this study is groundbreaking.
The levels of physical activity reported by the most active women in the new study were the equivalent of running 3.25 hours a week or walking 13 hours a week. The benefit of exercise was not linked to a particular sport or intensity, but related to total activity.
Dr. Colditz confirms, “You don’t have to be a marathon runner to get the risk-reducing benefits of exercise.”
Maruit SS, Willett WC, Feskanich D, Rosner B, Colditz GA. A prospective study of age-specific physical activity and premenopausal breast cancer. Journal of the National Cancer Institute. May 13, 2008 (advance online publication).
The research was funded by grants from the National Cancer Institute and the American Cancer Society.