Here's more evidence that leading an active lifestyle can lower risk of breast cancer.
Researchers from the American Cancer Society found that even moderate physical activity -- such as walking -- is linked with a 14 percent lower risk of breast cancer in postmenopausal women.
"Our results clearly support an association between physical activity and postmenopausal breast cancer, with more vigorous activity having a stronger effect," study researcher Alpa Patel, Ph.D., said in a statement. "Our findings are particularly relevant, as people struggle with conflicting information about how much activity they need to stay healthy. Without any other recreational physical activities, walking [an] average of at least one hour per day was associated with a modestly lower risk of breast cancer. More strenuous and longer activities lowered the risk even more."
The study, which is published in the journal Cancer Epidemiology, Biomarkers, and Prevention, is based on data from 73,615 postmenopausal women who were part of the CPS-II Nutrition Cohort study. Researchers looked at their breast cancer rates and physical activity rates over a 17-year period. By the end of that time period, 4,760 women had developed breast cancer.
At the start of the study, about one in 10 women didn't do any recreational exercise at all. Among the women who did exercise, they engaged in the metabolic equivalent of 3.5 hours of walking at a moderate pace each week. The most popular moderate-intensity exercises among the women who did exercise were dancing, aerobics, walking and cycling, while the more popular vigorous-intensity exercises were swimming, running and tennis.
Nearly half of the women in the study said that walking was the only recreational exercise they engaged in. Researchers found that walking really did seem to pay off: Those who walked seven hours a week had a 14 percent lower breast cancer risk, versus those who walked three or fewer hours a week.
And the more movement, the better -- vigorous exercise was linked with a 25 percent lower risk of breast cancer, compared with those who exercise the least.
"Current guidelines for adults recommend at least 150 minutes/week of moderate-intensity or 75 minutes/week of vigorous-intensity aerobic activity for overall health," researchers wrote in the study. "Yet, less than half of U.S. adult women are active at these minimum levels, and thus an even smaller proportion of women likely achieve the higher levels thought necessary for breast cancer risk reduction. Given that more than 60 percent of women report some daily walking, promotion of leisure-time walking may be an effective strategy for increasing physical activity among postmenopausal women."