The results of a new study add to the list of benefits seen with exercise among breast cancer survivors: reducing the risk of cardiovascular disease.
A 4-month exercise program reduced the risk of cardiovascular disease among breast cancer survivors who were considered sedentary and overweight or obese, a prospective, randomized, single-center clinical trial (ClinicalTrials.gov identifier: NCT01140282) published in JAMA Oncology showed.
These findings are the latest to show the various benefits exercise has for breast cancer patients. For instance, results from the EBBA-II trial (ClinicalTrials.gov identifier: NCT02240836) previously demonstrated that exercise during adjuvant treatment can improve cardiovascular function among breast cancer patients.
“It’s helpful in terms of proving that, for overweight breast cancer survivors, there’s definitely benefit to a regular exercise program,” said Polly Niravath, MD, breast medical oncologist at Houston Methodist Cancer Center, during an interview with Cancer Network. According to a 2016 study, women with early-stage breast cancer have nearly twice the risk of death from cardiovascular disease compared with breast cancer–free women.
Niravath said that discussions with patients typically focus on the benefits of exercise as it relates to breast cancer, such as reduced risk of recurrence. Now, she can discuss the benefit of a decreased risk of cardiovascular disease. “I think it’s great in terms of convincing patients that [exercise] is a worthwhile endeavor.”
The current trial enrolled women with early-stage breast cancer who were considered sedentary (less than 1 hour of structured exercise each week) and overweight or obese (body mass index of at least 25 or body fat of at least 30%). Trial eligibility also included not smoking and completing treatment within 6 months before enrollment.
A total of 100 women were randomized to either the exercise program group (n = 50) or usual care group (n = 50). Those in the exercise group participated in a supervised aerobic and resistance exercise regimen for 16 weeks. The exercise regimen consisted of at least 150 minutes of aerobic exercise weekly and 2 or 3 days of resistance exercise training weekly. Two women in the exercise group and 5 women in the usual care group did not complete the trial.
To determine the 10-year cardiovascular disease risk, the Framingham Risk Score (FRS) was used as a surrogate measure. The FRS was determined using age, systolic blood pressure, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, diabetes diagnosis, and smoking status.
At the completion of the 16 weeks, compared with the usual care group, women in the exercise group had significantly increased HDL cholesterol (P = .001) and decreased LDL cholesterol (P = .001), systolic blood pressure (P = .001), and diagnosis of diabetes (P < .001).
Niravath found the drop in diabetes particularly “impressive.” At the start of the study, 20 women in the exercise group had diabetes, and by the end, only 10 women had diabetes. “To be able to cut the risk of diabetes in half is phenomenal,” she said. “It really goes to show that there’s huge benefit for exercise.”
Overall, the FRS-predicted 10-year risk of cardiovascular disease was significantly lower among women in the exercise group compared with the usual care group (P < .001). Women in the exercise program group started with a 13% FRS-predicted 10-year risk of cardiovascular disease and ended with a 2% risk, translating to an 11-point drop. Niravath described this result as “a really significant drop.”
One limitation of the study, however, was the relatively small study size. Niravath noted that while implementing an exercise program is “pretty complicated” and “hard to do with really large numbers,” the study size is a drawback. “We saw such big differences after just 16 weeks of exercise…could this have been a little bit of a statistical fluke?” she wondered. She added that the findings should be replicated in a larger study.