Mild Physical Activity May Diminish Breast Cancer Risk

A new study has found that mild or intense physical activity either before or after menopause may decrease breast cancer risk; however, considerable weight gain may reverse these benefits.

Published early online in Cancer, the analysis done by University of North Carolina (UNC) at Chapel Hill researchers reveals that women can reduce their breast cancer risk by exercising and maintaining their weight.

Earlier studies have shown that physical activity reduces breast cancer risk, and researchers now sought to determine how often, how long, and how intense physical activity has to be to provide these benefits. Lauren McCullough, a doctoral candidate at the UNC Gillings School of Global Public Health, and her colleagues searched for a correlation between recreational physical activity, done at different time points in life, and the risk of developing breast cancer.

The study included women between the ages of 20 and 98: 1504 with breast cancer (233 noninvasive and 1271 invasive), and 1555 who did not have breast cancer. A reduced risk of developing breast cancer was discovered among the women who exercised either during the reproductive or the postmenopausal years. Women who exercised 10 to 19 hours per week experienced the greatest benefit, with an ~30% reduced risk. At all levels of intensity, reductions in risk were observed. Furthermore, 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 combined effects of physical activity, weight gain, and body size, they found that a significant gain in weight – particularly after menopause – led to an increased risk of developing breast cancer, even among active women. This indicated that weight gain could eliminate the beneficial effects of exercise on breast cancer risk.

Source: The University of North Carolina at Chapel Hill.