Physical Activity May Reduce Breast Cancer Risk. (News)
Women have had few options when it comes to reducing the risk of developing breast cancer, because many of the reported risk factors (such as genetics, early onset of menstruation, and menopause) remain out of their control. But mounting evidence now offers the hope that regular exercise and fat loss can give some protection. About three dozen studies have examined the question, with two-thirds showing a benefit, and one-third showing no benefit. Two of the most recent studies, however, give rise to optimism.
Preliminary results from a particularly encouraging study, the Women's Health Initiative, were reported last June at a meeting of the Society for Epidemiologic Research. Begun in 1993, this ongoing federal study has collected data from 66,568 American women age 50 and up. The data show that study participants who worked out vigorously for three or more hours each week were 13 percent less likely to develop breast cancer than nonexercisers. Women who worked out the most and burned the most fat were 22 percent less likely to develop breast cancer, possibly because lower levels of body fat do not store as much cancer-promoting estrogen.
If physical activity does help reduce the risk of breast cancer, questions such as "How much activity?" and "How intense?" still must be answered before prescriptive recommendations can be made. A study conducted by epidemiologists at the Alberta Cancer Board in Calgary in partnership with researchers from the University of Alberta attempted to answer those questions. …