Phase III randomized, placebo-controlled, double-blind trial of risedronate for the prevention of bone loss in premenopausal women undergoing chemotherapy for primary breast cancer.

PURPOSE Risedronate prevents bone loss in postmenopausal women. The purpose of this study was to determine whether risedronate prevents bone loss in premenopausal women undergoing chemotherapy for breast cancer. PATIENTS AND METHODS Premenopausal women undergoing chemotherapy for breast cancer were treated with oral calcium 600 mg and vitamin D 400 U daily and randomly assigned to receive oral risedronate 35 mg weekly or placebo, with all these therapies beginning within a month of the start of chemotherapy. Most chemotherapy regimens included anthracyclines, taxanes, or cyclophosphamide. Bone mineral density (BMD) was measured at baseline and 1 year. The primary end point was the change in lumbar spine (LS) BMD from baseline to 1 year. RESULTS A total of 216 women enrolled; 170 women provided BMD data at 1 year. There was no difference in the mean change or percent change in LS BMD between groups, with a loss of 4.3% in the risedronate arm and 5.4% for placebo at 1 year (P = .18). Loss of BMD at the femoral neck and total hip were also similar between treatment groups. Risedronate was well tolerated, with no significant differences in adverse events compared with placebo, except that arthralgias and chest pain were worse in those receiving the placebos. CONCLUSION Risedronate did not prevent bone loss in premenopausal women undergoing adjuvant chemotherapy for breast cancer.