Adjuvant use of zoledronic acid did not improve disease-free survival (DFS) in women with stage II/III breast cancer treated with adjuvant chemotherapy, concluded AZURE (Adjuvant Zoledronic Acid to Reduce Recurrence), one of the largest bisphosphonate trials conducted to date.
At 5-year follow-up, no difference in DFS was observed between women who received zoledronic acid and those who did not. However, one surprising finding was that zoledronic acid did benefit a subgroup of women with well-established menopause: a 29% improvement in overall survival (P = .017) as well as improvement in DFS (P < .001) was observed, said Robert Coleman, MD, professor of medical oncology at the University of Sheffield, United Kingdom, in presenting the results during the 33rd CTRC-AACR San Antonio Breast Cancer Symposium. No benefit was observed in premenopausal women.
These subgroup results are consistent with those previously reported by the Austrian Breast & Colorectal Cancer Study Group (ABCSG-12), which found the addition of 3 years of zoledronic acid to hormonal therapy following surgery for breast cancer in premenopausal women with induced menopause improved DFS by 32%. Dr. Coleman said the AZURE results suggest zoledronic acid does not have a direct anticancer effect and hypothesized that adjuvant bisphosphonate efficacy may depend on a low estrogen/inhibin concentration within the bone microenvironment.
AZURE randomized 3,360 patients from 174 centers in seven countries to adjuvant chemotherapy and/or endocrine therapy with zoledronic acid (n = 1,681) or without (n = 1,678) for 5 years. The treatment groups were well balanced, including lymph node status, tumor stage, estrogen-receptor status, menopausal status, type of chemotherapy, and statin use.
Following Dr. Coleman’s presentation, Sharon H. Giordano, MD, MPH, The University of Texas M.D. Anderson Cancer Center, outlined implications for patient care based on the AZURE results: routine adjuvant use of zoledronic acid to prevent recurrence is not indicated; differences in outcome by menopausal status are intriguing but not definitive; and bisphosphonates continue to have an important role in treating bone loss among women with breast cancer.