Exercise reduces the risk of breast cancer for all women at all risk levels, even exercise programs begun after menopause. A study conducted by researchers at Fred Hutchinson Cancer Research Center found that the activity does not have to be strenuous, but it should be consistent to obtain the maximum benefit. Brisk walks five days a week can reduce your risk by 20%, according to Anne McTiernan, M.D., Ph.D., lead investigator and director of the Prevention Center.

Why does exercise have such a positive effect? Fatty tissue produces hormones such as estrogen, which has been linked to breast cancer risk. Exercising and losing weight reduces the production of estrogen, thereby reducing the risk of developing breast cancer.

According to an article in the Journal of the American Medical Association dated September 10, 2003, "physical inactivity may be a modifiable breast-cancer risk factor in older women." Activities such as swimming, walking, or biking are easily incorporated into most women's lives. Regular exercise even reduces the incidence of breast cancer among women with higher risk factors such as a strong family history or participation in hormone replacement therapy.

Women who were of normal or low weight benefited more from the equivalent of walking 10 hours a week, but those who were obese or overweight did not appear to reduce their risk with exercise. However, these women should not be discouraged from developing a regular exercise plan since it may help them achieve weight loss. If overweight women can get their weight down, according to Dr. McTiernan, they can gain the risk reducing benefits of regular moderate exercise.

Fred Hutchinson Cancer Research Center: "Exercise and Breast-cancer Prevention: Study Finds It's Never Too Late to Start, and the Activity Need Not Be Strenuous," Fred Hutchinson Cancer Research Center.