Exercise, even mild physical activity, may reduce breast cancer risk
Women who exercised either during their reproductive or postmenopausal years had a reduced risk of developing breast cancer. Women who exercised 10 to 19 hours per week experienced the greatest benefit with an approximate 30 percent reduced risk. Risk reductions were observed at all levels of intensity, and exercise seemed to reduce the risk of hormone receptor positive breast cancers, the most commonly diagnosed tumor type among American women.
“The observation of a reduced risk of breast cancer for women who engaged in exercise after menopause is particularly encouraging given the late age of onset for breast cancer,” McCullough said.
When the researchers looked at the joint effects of physical activity, weight gain and body size, they found that even active women who gained a significant amount of weight – particularly after menopause – had an increased risk of developing breast cancer, indicating that weight gain can eliminate the beneficial effects of exercise on breast cancer risk.