Is there a connection between exercise and breast cancer risk?

Is there a connection between exercise and breast cancer risk?

29 Oct 2015

Regular physical activity could play a role in helping women at high-risk of breast cancer delay the need for drastic preventive measures such as prophylactic mastectomy, according to new research led by the Perelman School of Medicine at the University of Pennsylvania.

A drop of 10% in estrogen-sensitive breast tissue per 100 minutes of exercise

In the study, the team recruited 139 premenopausal women aged 18-50 who were all deemed high-risk for breast cancer due to genetic mutations or family history. The “low-dose” group performed a treadmill exercise 150 minutes per week. The “high-dose” group exercised twice that amount. A control group exercised for less than 75 minutes per week. Each woman provided blood and urine samples, and also underwent MRI breast imaging, before and after each of five menstrual cycles.

Over the course of the study, the control group showed a 20% increase in estrogen-sensitive breast tissue, as measured by MRI, whereas the low- and high-dose groups saw reductions of about 8% and 12% respectively—implying a drop of about 10% per 100 minutes of exercise.

Suggestions for women with an elevated breast cancer risk

Results of the study help clarify the emerging connection between exercise and breast cancer risk. As a result of the new findings, the authors suggest that women who have an elevated breast cancer risk or worry about having such risk should consider doing 30 to 60 minutes of aerobic activity per day for five days per week.


“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.” said Kathryn H. Schmitz, PhD, MPH, FACSM, a professor of Epidemiology and a member of the Abramson Cancer Center at Penn Medicine.

“Exercise could delay the diagnosis”

“This research shows one more potential benefit of exercise for women at high risk for breast cancer,” said Sue Friedman, executive director of the nonprofit organization Facing Our Risk of Cancer Empowered (FORCE), which helped recruit women for the study. "We hope this will lead to further research on ways in which high risk women can reduce their breast cancer risk.”

“We understand that exercise isn’t a panacea that will prevent cancer from occurring in women at high risk,” Schmitz said. “However, we do believe that exercise could delay the diagnosis, and reduce the stage and grade and severity of the tumor when it is diagnosed” said Schmitz.

Source: Perelman School of Medicine

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