(HealthDay News) — During the reproductive and postmenopausal years, recreational physical activity (RPA) at any intensity level is associated with reduced breast cancer risk, according to a study published online June 25 in Cancer.
To examine the association between RPA and breast cancer risk, Lauren E. McCullough, M.S.P.H., from the University of North Carolina at Chapel Hill, and colleagues conducted a population-based study involving 1,504 breast cancer cases (233 in situ, 1,271 invasive) and 1,555 controls (aged 20 to 98 years) from the Long Island Breast Cancer Study Project.
During the reproductive period and after menopause the researchers observed a nonlinear dose-response association between breast cancer risk and RPA. The greatest benefit was seen for women in the third quartile of activity, with a significant decrease in risk for reproductive (odds ratio [OR], 0.67) and postmenopausal activity (OR, 0.70). Neither intensity of activity nor hormone receptor status influenced risk. Women with unfavorable energy balance profiles were at increased breast cancer risk based on joint assessment of RPA, weight gain, and body size assessment. There was a significant multiplicative interaction between RPA and adult weight gain.
“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 in a statement.