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.