Risedronate prevents bone loss in breast cancer survivors: a 2-year, randomized, double-blind, placebo-controlled clinical trial.

Purpose: Limited data are available on the efficacy of oral bisphosphonate therapy in breast cancer survivors. Our goal was to examine prevention of breast cancer-related bone loss in this cohort.
Patients and Methods: Eighty-seven postmenopausal women after chemotherapy for breast cancer were randomly assigned to once-weekly risedronate 35 mg or placebo for 24 months. Outcomes included bone mineral density (BMD) and turnover markers.
Results: At study initiation, 13% of patients were on an aromatase inhibitor (AI). After 24 months, there were differences of 1.6 to 2.5% (P < .05) at the spine and hip BMD between the placebo and risedronate groups. At study completion, 44% were on an AI. Adjusting for an AI, women on placebo plus AI had a decrease in BMD of (mean +/- SE) 4.8% +/- 0.8% at the spine and 2.8% +/- 0.5% at the total hip (both P < .001). In women on risedronate + AI, the spine decreased by 2.4% +/- 1.1% (P < .05) and was stable at the hip. Women in the placebo group not on an AI, maintained BMD at the spine, and had a 1.2% +/- 0.5% loss at the total hip (P < .05). Women who received risedronate but no AI had the greatest improvement in BMD of 2.2% +/- 0.9% (P < .05) at the total hip. Bone turnover was reduced with risedronate. There were no differences in adverse events between the groups.
Conclusion: We conclude that in postmenopausal women with breast cancer with or without AI therapy, once-weekly oral risedronate was beneficial for spine and hip BMD, reduced bone turnover, and was well tolerated.