The effect of exercise on body composition and bone mineral density in breast cancer survivors taking aromatase inhibitors.

OBJECTIVE: This study examined the effect of 12 months of aerobic and resistance exercise versus usual care on changes in body composition in postmenopausal breast cancer survivors taking aromatase inhibitors (AIs). METHODS: The Hormones and Physical Exercise study enrolled 121 breast cancer survivors and randomized them to either supervised twice-weekly resistance exercise training and 150 min/wk of aerobic exercise (N = 61) or a usual care (N = 60) group. Dual-energy X-ray absorptiometry scans were conducted at baseline, 6 months, and 12 months to assess changes in body mass index, percent body fat, lean body mass, and bone mineral density. RESULTS: At 12 months, the exercise group relative to the usual care group had a significant increase in lean body mass (0.32 vs. -0.88 kg, P = 0.03), a decrease in percent body fat (-1.4% vs. 0.48%, P = 0.03), and a decrease in body mass index (-0.73 vs. 0.17 kg/m2 , P = 0.03). Change in bone mineral density was not significantly different between groups at 12 months (0.001 vs. -0.006 g/cm2 , P = 0.37). CONCLUSIONS: A combined resistance and aerobic exercise intervention improved body composition in breast cancer survivors taking AIs. Exercise interventions may help to mitigate the negative side effects of AIs and improve health outcomes in breast cancer survivors.