New study findings bolster the idea that regular exercise throughout life can help reduce a woman's risk of breast cancer before and after menopause.
The benefit may be "modest," but the new findings from Researchers at the State University of New York at Buff add to those of earlier research suggesting that regular exercise offers some protection against breast cancer.
The study of 1,550 women with and without breast cancer found that regular, strenuous activity like jogging, biking and aerobics was associated with a lower risk of the disease. In particular, pre- and postmenopausal women who reported being highly active 20 years before the study had about half the breast cancer risk of women who were inactive throughout their lives.
A number of studies have suggested an active lifestyle may help protect against breast cancer, but some have found no relationship between the two. In addition, the findings for premenopausal and postmenopausal women have been inconsistent in some studies. Similarly, the new research found differences between younger and older women.
Participants, who were 40 to 85 years old, were asked to recall how often they engaged in sports and exercise "long enough to work up a sweat" at four points in their lives: at age 16 and 20, 10 and two years before the study.
The researchers found that postmenopausal women who said they regularly got such activity (just under two hours a week, on average) at all four time points had a lower breast cancer risk. This was not true of premenopausal women.
However, in both groups, the women who were most active 20 years before--getting, on average, three-and-a-half hours of strenuous exercise a week--were about half as likely to develop breast cancer as those who were consistently inactive.
Walking for exercise was not related to breast cancer risk in either group of women. However, some past studies have tied moderate exercise, including walking, to a reduced risk of the disease among younger and older women.
The reasons for the varying findings for pre- and postmenopausal women in this study are unclear, according to the researchers. They point out that a relatively small number was highly active: Overall, participants' exercise levels were "modest," and only a small percentage got the 30 minutes of exercise each day that is recommended for healthy adults.
Some research suggests that even higher activity levels may be necessary to make a significant dent in breast cancer risk. Still, the study supports current recommendations that women incorporate physical activity into their daily lives throughout their lifespans.
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