BISPHOSPHONATE RISEDRONATE PREVENTS BONE LOSS IN WOMEN WITH ARTIFICIAL MENOPAUSE DUE TO CHEMOTHERAPY OF BREAST-CANCER - A DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY

Purpose: To determine the effectiveness and safety of the bisphosphona te risedronate in preventing bone loss in young women with breast canc er and early menopause induced by chemotherapy who are at major risk f or the development of postmenopausal osteoporosis. Patients and Method s: Fifty-three white women, aged 36 to 55 years, with breast cancer an d artificially induced menopause were stratified according to prior ta moxifen use. Thirty-six patients received tamoxifen (20 mg/d). Within each stratum, patients were randomly assigned to receive risedronate ( n = 27) or placebo (n = 26). Treatment consisted of eight cycles oral risedronate 30 mg/d or placebo daily for 2 weeks followed by 10 weeks of no drug (12 weeks per cycle). Patients were monitored for a third y ear without treatment. Results: Main outcomes of the study were change s in lumbar spine and proximal femur (femoral neck, trochanter, and Wa rd's triangle) bone mineral density (BMD), and biochemical markers of bone turnover. In contrast to a significant decrease of BMD at the lum bar spine and hip in the placebo group, there wets an increase in BMD in the risedronate group. On treatment withdrawal, bone loss ensued, w hich suggests that treatment needs to be continuous to maintain a prot ective effect on bone mass. At 2 years, the mean difference (+/- SEM) between groups was 2.5% +/- 1.2%, (95% confidence interval [CI], 0.2 t o 4.9) at the lumbar spine (P = .041) and 2.6% +/- 1.1%, (95% CI, 0.3 to 4.8) at the femoral neck (P = .029). Similar results were observed at the hip trochanter. Results by stratum indicate a beneficial, altho ugh partial, effect of tamoxifen in reducing bone loss. Risedronate wa s well tolerated and showed a good safety profile, with no evidence of laboratory abnormalities. Conclusion: Risedronate appears to be a saf e treatment that prevents both trabecular and cortical bone loss in wo men with menopause induced by chemotherapy for breast cancer. (C) 1997 by American Society of Clinical Oncology.