Exercise may lower breast cancer risk

October 7, 2003 in Cancer Prevention, Nutrition Topics in the News, Sports Nutrition and Exercise, Women's Health

Exercise may lower breast cancer risk

Participating in regular physical "recreational" activity, even for just a few hours a week, may significantly lower a woman's risk of developing early, localized breast cancer, what doctors call breast carcinoma in situ (BCIS).

Researchers from the University of Southern California compared the self-reported exercise habits of 567 women diagnosed with BCIS with that of 616 "control" women who did not have the disease. All of the women were between the ages of 35 and 64.

After factoring out known breast cancer risk factors, such as a history of cigarette smoking and use of hormone replacement therapy, they found that overall the risk of BCIS was roughly 35% lower among women who reported "any" physical activity compared to physically inactive women. This level of reduced risk remained fairly constant with increasing levels of activity.

However, when the investigators subdivided the women into those with and without a family history of breast cancer, they found no reduction in breast cancer risk among women with a mother or sister with the disease.

In general, doctors are not exactly sure how physical activity may guard against early breast cancer but they have several theories. Exercise may lower levels of female hormones, especially during adolescence.

The known ability of exercise to boost the immune system and make a person more sensitive to insulin may also play a role.

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