Study Examines Power of Exercise to Prevent Breast Cancer

A new federally funded University of Pennsylvania School of Medicine study aims to learn whether women at high risk of breast cancer can use exercise to meaningfully reduce their risk of getting the disease. Building on evidence that reducing estrogen in the body reduces cancer risk, and that elite female athletes experience a drop in estrogen levels that often cause them to stop ovulating and menstruating, the WISER Sister trial will investigate two different levels of regular treadmill exercise as a possible intervention for breast cancer risk reduction.

The stakes for women who carry BRCA genetic mutations are high – as many as 80 percent of them will develop breast or ovarian cancer during their lives – but options for risk reduction are drastic and few, and the choices may be unacceptable to some women. Previous Penn research shows that prophylactic mastectomy slashes carriers’ breast cancer risk by 90 percent, while prophylactic oophorectomy, or ovary removal, halves their breast cancer risk and reduces their chances of getting of ovarian cancer by about 85 to 90 percent. Though the surgeries are highly effective, they usher in quality of life concerns – particularly with regard to body image and sexuality – and the early menopause that results from ovary removal brings a woman’s childbearing years to an end. And the procedures aren’t recommended for women who have a family history of breast cancer but don’t carry the mutated genes.

“The decision to have these surgeries is so difficult that many women delay them, sometimes with terrible consequences. We would like to find out if exercise could buy high-risk women time they need to more safely think through their options,” says Kathryn Schmitz, PhD, MPH, an assistant professor in the Center for Clinical Epidemiology and Biostatistics who is leading the new study, in partnership with Susan Domchek, MD, director of the Abramson Cancer Center’s Cancer Risk Evaluation Program. “Exercise also has a number of health and stress reduction benefits that make it even more attractive for this population.”

Over the next three years, Schmitz's team will enroll 160 women ages 18 to 40, who must have an elevated risk of getting breast cancer based on her family history of the disease. BRCA carriers will be included among eligible women. However, participants will not be required to undergo genetic testing.

Previous research on estrogen exposure strongly suggests that reducing estrogens will result in reduced breast cancer risk in this population. The investigators plan to use their findings to offer effective exercise guidelines for high-risk women. Unlike surgery, exercise is a low-cost intervention with few side effects, so Schmitz is hopeful that the study results will offer risk-reduction tools to a larger swath of high-risk women, including minorities and other groups that may be underserved or lack access to genetic testing or proper early screening.

“We are interested in rigorously investigating all potential options to decrease cancer risk,” says Domchek, an associate professor of Medicine in the division of Hematology/Oncology. “Exercise is a wonderful intervention due to its numerous health benefits. However, it is important for us to quantify the amount of exercise needed and the potential benefits such exercise might provide.”