Exploratory, unplanned analysis of randomized trial supports big effect
Rigorous exercise dramatically lowered heart disease risk for overweight and obese survivors of early stage breast cancer, a secondary analysis of randomized trial data found.
The mean overall Framingham Risk Score (FRS) scores dropped by 11 percentage points with a 16-week exercise program to a mean 2.0% predicted 10-year risk of an event whereas it stayed 13.0% in the usual care group (P<0.001), reported Christina Dieli-Conwright, PhD, MPH, of the University of Southern California, Los Angeles, and colleagues in JAMA Oncology.
The findings were similar for total Framingham score in this initially sedentary population and were driven by big reductions in systolic blood pressure (13.7 mm Hg lower vs controls after the intervention), LDL cholesterol (48.6 mg/dL lower), and diabetes diagnoses (20% fewer vs an increase of 9%).
"This study further supports the idea that aerobic and resistance exercise, which has been shown to favorably affect metabolic syndrome in women with early stage breast cancer, reduces the 10-year risk of cardiovascular disease significantly, as determined by the FRS score -- further evidence that lifestyle changes can be very important in patients including those with breast cancer," commented C. Kent Osborne, MD, of Baylor College of Medicine in Houston.
"Oncologists should emphasize these data as part of the survivorship plan for such patients," he told MedPage Today.
The substantial effects relative to other studies may reflect the patients chosen, particular exercise regimen, or both, suggested Osborne, who was not involved in the study.
Dieli-Conwright's group randomized 50 patients to the usual care group and and 50 patients to the exercise group. The patients were a mean age of 53.5 years and 55% were Hispanic.
The women were either obese or overweight as indicated by a body mass index of ≥25.0 or body fat of ≥30%, had completed cancer treatment within 6 months before enrollment, were sedentary, and had stage I to III breast cancer.
Participants in the exercise arm did 50 to 80 minutes of supervised resistance and aerobic exercise three times a week for a total of 16 weeks. Resistance exercise included tricep pull downs, chest presses, bicep curls, leg presses, leg extensions or flexions, and seated rows. Aerobic exercises included cycling, machine rowing, and treadmill walking.
The intervention was targeted to meet American College of Sports Medicine/American Cancer Society exercise guidelines for cancer survivors of at least 150 minutes of aerobic exercise and 2 to 3 days of resistance exercise training per week.
FRS "was calculated using female-specific validated methodology," the researchers noted. Mixed-model repeated-measures analyses assessed differences in average changes for outcomes on an intent-to-treat basis.
Dieli-Conwright acknowledged the study's small sample size as a limitation.
Also, "the study was not designed specifically to target Framingham Risk Score. It was designed to target metabolic syndrome, but some of the health factors overlap there," Dieli-Conwright told MedPage Today. The study met that primary endpoint, as previously reported.
Another limitation was the exclusion of smokers, "and one of the factors to calculate the score is smoking, so by nature, we did not have any smokers so we didn't have any improvement in the smoking outcome per se," Dieli-Conwright noted.
"The Framingham Risk Score itself has some limitations. While it has been validated before and it's been used in other populations to assess cardiovascular disease risk, perhaps it's not the most valid score to assess whether or not an individual is going to develop heart disease. So, for instance, it doesn't count for inflammation or blood glucose or hemoglobin A1C, some other strong factors that are associated with risk of developing heart disease," she added.
This study was funded by the National Cancer Institute and the National Center for Advancing Translational Sciences of the National Institutes of Health.
Dieli-Conwright did not report any disclosures.
Source Reference: Lee K, et al "Effect of aerobic and resistance exercise intervention on cardiovascular disease risk in women with early-stage breast cancer a randomized clinical trial" JAMA Oncol 2019; DOI: 10.1001/jamaoncol.2019.0038.
Read the original article on Medpage Today: Exercise Cuts CVD Risk After Breast Cancer