DOCTOR'S VIEW ARCHIVE

Exercise Reduces Risk of Breast Cancer

OSLO, NORWAY - Breast cancer is a serious and prevalent form of cancer. While men can develop breast cancer, it is 200 times more likely in women and affects one in every eight women in the United States. The risk of breast cancer is especially increased in those women who are older, begin menstrual periods early, experience menopause late, bear fewer children or begin having children later in life. A history of breast cancer in the family increases the risk of developing breast cancer in a woman by three to five times.

Dr Inger Thune and associates reported the findings of their survey study of over 25 thousand women. Their data, reported recently in the New England Journal of Medicine (1997;336:1269-75), showed that four hours or more of exercising a week significantly reduced their risk of developing breast cancer. The risk was also reduced with higher levels of activity in the workplace (lifting, walking, or manual labor).

This study provides convincing evidence that regular physical activity can reduce the risk of breast cancer in women.

In an accompanying journal editorial, Dr. Anne Tiernan points out several possible mechanisms to explain this impact of exercise on women. These include the effects of exercise on female hormone levels, reduced obesity, as well as possible beneficial effects of exercise on the immune system and body metabolism.

Dr. Tiernan recommends that women exercise whether or not it will prevent breast cancer. She highlights the known benefits of exercise: reduced overall mortality, heart disease, diabetes mellitus, stroke, osteoporosis, disability, and obesity, in addition to lessening the impact of arthritis. The Medical Editors of MedicineNet.com agree.

For more information, please visit the Breast Cancer Center of MedicineNet.com.