Breast cancer and cardio have long had a symbolic connection through fundraising events like the Susan G. Komen Foundation’s Race for the Cure, but a growing body of research is linking exercise to this disease in a very concrete way.
Scientists have found what may prove to be one of the key missing links between the amount of exercise a woman gets and her likelihood of developing this dreaded diagnosis, which affects one in eight women and kills an estimated 40,000 Americans a year.
The study, published this week in the journal Cancer, Epidemiology, Biomarkers & Prevention, compared a control group of young, healthy, but sedentary women with a group that did 30 minutes of moderate-to-vigorous cardio five times a week for 16 weeks.
The researchers found a significant difference between the groups in how their bodies broke down estrogen into smaller components, or metabolites, that have already been linked to breast cancer.
They found that the exercise group produced significantly more of a “good” metabolite that’s been shown to lower the risk of breast cancer, while the control group saw no such change.
“Observational studies suggest physical activity lowers breast cancer risk, but there are no clinical studies that explain the mechanism behind this,” said study co-author Mindy S. Kurzer of the University of Minnesota in Saint Paul. “Ours is the first study to show that aerobic exercise influences the way our bodies break down estrogens to produce more of the ‘good’ metabolites that lower breast cancer risk.”
Exercise has also been shown to dramatically reduce the likelihood of death after a breast cancer diagnosis. A 2008 study showed a 45 percent reduction in the risk of death for women who did the equivalent of 2 to 3 hours of brisk walking a week, and a four-fold increase for women who exercised less after diagnosis.