In an 8-year follow-up of a Korean phase III trial (ASTRRA) reported in the Journal of Clinical Oncology, Baek et al evaluated the effects of adding adjuvant ovarian function suppression to tamoxifen in premenopausal patients with estrogen receptor (ER)-positive breast cancer, with a focus on the disease-free survival benefit.
In the multicenter trial, 1,282 premenopausal patients aged < 45 years who had undergone surgery and who had completed neoadjuvant or adjuvant chemotherapy were randomly assigned between March 2009 and March 2014 to receive 5 years of tamoxifen with ovarian function suppression for 2 years or 5 years of tamoxifen alone. At 5-year analysis, the tamoxifen plus ovarian function suppression group had superior disease-free survival (the study’s primary endpoint) and overall survival vs the control group. The current analysis includes 1,231 patients with long-term follow-up data, including 610 in the tamoxifen plus ovarian function suppression group and 621 in the control group.
Median follow-up was 106.4 months. Disease-free survival at 8 years was 85.4% in the tamoxifen plus ovarian function suppression group vs 80.2% in the control group (hazard ratio [HR] = 0.67, 95% confidence interval [CI] = 0.51–0.87). Sites of first disease-free survival events were: local, regional, or distant recurrence in 11.7% vs 17.3%; contralateral breast cancer in 1.4% vs 0.8%; death without recurrence in 0.3% vs 0.8%; and other primary cancer in 1.3% vs 2.6%.
Overall survival at 8 years was 96.5% in the tamoxifen plus ovarian function suppression group vs 95.3% in the control group (HR = 0.78, 95% CI = 0.49–1.25).
The investigators concluded, “Adding ovarian function suppression for 2 years to adjuvant tamoxifen with a longer follow-up resulted in consistent disease-free survival benefits, suggesting that adding ovarian function suppression to tamoxifen should be considered for patients who remain in a premenopausal state or resume ovarian function after chemotherapy.”
Hee Jeong Kim, MD, PhD, of the Division of Breast Surgery, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute, funded by the Ministry of Health & Welfare. For full disclosures of the study authors, visit ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.