Randomized Trial of Adjuvant Zoledronic Acid in Postmenopausal Women With High-Risk Breast Cancer

Purpose: We present the results of a randomized multicenter clinical trial of adjuvant zoledronic acid (ZA) in postmenopausal women with high-risk breast cancer. The primary objective was change in bone mineral density (BMD) at the lumbar spine and femoral neck at 1 year. Secondary objectives included change in calcaneal BMD, disease-free survival (DES), overall survival (OS), and toxicity. Patients and Methods: Postmenopausal women with stage II/III breast cancer diagnosed up to 5 years previous were eligible and randomized to either observation or ZA 4 mg intravenous every 3 months. Bone mineral density testing was performed at 0, 6, and 12 months. Results: Sixty-eight women were enrolled (36 ZA and 32 observation). The population was a median of 2 years from diagnosis and the majority received tamoxifen during the study. There. was a significant difference in the mean change from baseline to 1 year follow-up for lumbar spine (increased by 4.28% +/- 0.62%; P = .01), total femur (increased by 1.9% +/- 0.4%; P = .03), trochanter (increased by 2.97% +/- 0.69%; P = .03), and calcaneal BMD (increased by 2% +/- 0.57%; P = .01) in favor of the ZA arm. No significant difference in the mean change for the femoral neck was seen. No significant differences in DFS or OS were observed. Conclusion: Zoledronic acid significantly improved the BMD at multiple skeletal sites in postmenopausal women largely on tamoxifen. No new safety signals were noted. There were insufficient events to comment on DFS or OS.