Adding ovarian function suppression to tamoxifen in young women with hormone-sensitive breast cancer who remain premenopausal or resume menstruation after chemotherapy: 8-year follow-up of the randomized ASTRRA trial.
Soo Yeon Baek, Woo Chul Noh, Sei‐Hyun Ahn, Hyun‐Ah Kim, Jai Min Ryu, Seung Il Kim, Eun‐Gyeong Lee, Seock‐Ah Im, Yong Sik Jung, Min Ho Park, Kyong Hwa Park, Su Hwan Kang, Joon Jeong, Eun Hwa Park, Sung Yong Kim, Min Hyuk Lee, Lee Su Kim, Woosung Lim, Seon‐Ok Kim, Hee Jeong Kim
Abstract
506 Background: Addition of Ovarian Suppression to Tamoxifen in Young Women With Hormone-Sensitive Breast Cancer Who Remain Premenopausal or Regain Vaginal Bleeding After Chemotherapy (ASTRRA) trial, at 63 months median follow-up, showed that the addition of 2 years of ovarian function suppression (OFS) to Tamoxifen (TAM) significantly improved disease-free survival (DFS) compared with TAM alone in patients with hormone receptor–positive breast cancer who remain in a premenopausal state or resume ovarian function after chemotherapy. We report updated long-term outcomes from ASTRRA trial with 106.4 months median follow-up. Methods: This study is a post-trial follow-up of the ASTRRA trial, which randomly assigned 1,298 patients with breast cancer in a 1:1 ratio to receive TAM only (n = 647) or TAM + OFS (n = 635). The primary endpoint was DFS and secondary endpoint was overall survival (OS). We used Kaplan-Meier estimates for time to event endpoints and hazard ratios (HR) with 95% confidence interval (CI) from Cox-regression model. Results: At 106.4 months of median follow-up, there continues to be a statistically significant reduction in DFS event rate in favor of the TAM+OFS group. The estimated 8-year DFS rate was 85.4% in the TAM + OFS group and 80.2% in the TAM-only group (HR 0.67; 95% CI, 0.51 to 0.87). There were no significant differences in OS between two groups. The estimated 8-year OS rate was 96.5% in the TAM + OFS group and 95.3% in the TAM-only group (HR, 0.78; 95% CI, 0.49 to 1.25). The results of DFS and OS between the two groups defined from the time of random assignment to the time of events were also similar. Conclusions: These data demonstrate consistent survival advantages of adding OFS 2 years to TAM treatment over time, with the long-term follow-up reported to date. This study finding suggest that adding OFS to TAM should be considered for those who remain in a premenopausal state or resume ovarian function after chemotherapy. Longer follow-up is needed to fully evaluate the OS benefit.