CHICAGO — There was no difference in disease-free survival between premenopausal women with breast cancer who received tamoxifen and those who received anastrozole.
The addition of zoledronic acid to both adjuvant endocrine therapies improved the disease-free survival and the relapse-free survival, according to Michael Gnant, MD, a professor of surgery at the Medical University of Vienna. Gnant presented this data from the Austrian Breast and Colorectal Cancer Study
Group Trial 12 at an ASCO 2008 Annual Meeting Plenary Session.
“These results are a reassuring outcome and add to the growing evidence that premenopausal women with low to intermediate risk and high endocrine responsive tumors can safely and efficiently be treated without adjuvant chemotherapy,” Gnant said. “Adjuvant treatment with zoledronic acid should be considered to improve the standard of care in these women.”
From 1999 to 2006, 1,803 premenopausal women with stage I or II hormone-responsive breast cancer received goserelin after surgery and were randomly assigned to tamoxifen with or without zoledronic acid or anastrozole with or without zoledronic acid. After a median follow up of five years, there was no difference between those who received anastrozole and those who received tamoxifen.
The addition of zoledronic acid, however, improved the disease-free survival by 36% compared with endocrine therapy alone. Zoledronic acid also reduced the risk of recurrence by 35% vs. endocrine therapy alone. There was also a trend toward improved overall survival favoring the zoledronic acid.
The treatments were well-tolerated and there were no unexpected adverse effects. There were no instances of osteocronosis of the jaw or renal toxicity, which can be associated with bisphosphonates.
Gnant M, Mlineritsch B, Schippinger W, et al. #LBA4. Presented at: 2008 ASCO Annual Meeting; May 3-June 3. Chicago.
There have been several randomized trials that have been conducted in this setting, though not specifically with zoledronic acid, and they have yielded mixed results. At the moment, we do not need to draw conclusions about all women with breast cancer. We will have additional data within the next 12 to 24 months.
– Eric Winer, MD
Director of Breast Oncology, Dana-Farber Cancer Center