Regular physical activity could allow women at high-risk of developing breast cancer to delay drastic preventive measures like prophylactic mastectomy, a new study published in the journal Breast Cancer Research and Treatment has shown.

“Women who discover that they are at an increased risk of breast cancer, perhaps from an inherited gene mutation, have no easy option for avoiding cancer. Double mastectomy is considered an effective method of prevention, but that’s an incredibly difficult decision to make,” said Kathryn H. Schmitz, PhD, MPH, FACSM, a professor of Epidemiology and a member of the Abramson Cancer Center at Pennsylvania University Perelman School of Medicine.

Because estrogen has been linked in the relationship between aerobic exercise and a reduction in breast cancer risk, researchers sought to evaluate whether aerobic exercise would impact breast tissue in women at high-risk for the disease.

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For the study, researchers enrolled 139 premenopausal women between the ages of 18 and 50 who were at high-risk for developing breast cancer due to genetic mutations or family history.

Participants were randomly assigned to perform a treadmill exercise for 150 minutes per week (low-dose), a treadmill exercise for twice the duration as the low-dose group (high-dose), or a control group that exercised for less than 75 minutes per week.

Results showed that the control group displayed a 20% increase in estrogen-sensitive breast tissue, while the low-dose and high-dose groups had observed reductions of about 8% and 12%, respectively, suggesting that 100 minutes of exercise reduces the amount of estrogen-sensitive breast tissue by about 10%.

“These new results show that for women in this high-risk category, aerobic exercise has a striking ability to reduce the hormonally sensitive tissue in the breast that we worry about most for breast cancer.”


1. Exercise could give margin of safety to women who want to delay preventive mastectomy [news release]. EurekAlert! website. October 29, 2015. Accessed October 30, 2015.