Background: Oncotype RS is a 21-gene assay used to predict the risk of recurrence and benefit from chemotherapy in early-stage, hormone positive (HR+), node-negative breast cancer (BC). The TAILORx trial showed that many patients with RS<25 can avoid chemotherapy and the small absolute benefit may be due to chemotherapy-induced menopause in premenopausal patients. The SOFT-TEXT trials found that premenopausal women have higher rates of freedom from recurrence and 8-year survival when receiving OS with endocrine therapy (ET). These studies suggest that premenopausal women with IR RS (16-25) benefit from aggressive ET with OS but trends in OS use have not been adequately studied. We predict that OS use has increased in premenopausal patients over time. Methods: We identified 87 premenopausal patients with early-stage, HR+ BC with IR Oncotype RS (16-25) who were treated with ET between 2006-2020 at our large NYC academic cancer center. The Cochran-Armitage test was used for trends in the proportions of patients receiving OS and chemotherapy over time. The log-rank test was used to compare distributions of recurrence rates between RS groups. Results: Median age was 46 years and median RS was 19. Overall, 23 (26%) patients received chemotherapy and 30 (34%) received OS (via leuprolide, goserelin or surgical oophorectomy) with ET. 55 (63%) received tamoxifen alone, 10 (11%) tamoxifen + OS, and 20 (23%) aromatase inhibitor (AI) + OS. Between 2006-2010, 2 (17%) patients received OS and 2 (17%) received chemotherapy compared to 9 (24%) and 12 (32%) between 2011-2015, and 19 (51%) and 9 (24%) between 2016-2020, respectively (Table). There was a significant increasing proportion of patients receiving OS; p=0.0064, but no significant trend in chemotherapy receipt; p=0.8910. There were 8 (9%) patients that recurred, with a borderline significant difference in secondary invasive breast event rates in patients receiving tamoxifen alone (8, 15%) compared to those on tamoxifen + OS or AI + OS (0, 0%), (p=0.0520). There were no significant differences in recurrence rates based on chemotherapy receipt (p=0.1868) or RS group 16-20 vs 21-25 (p= 0.1836). Conclusions: There has been a significant increase in the use of OS with ET in premenopausal women with IR RS in our study population. This study shows how the results of the SOFT-TEXT trial have been adapted into current practice. Future studies are needed to evaluate real-world recurrence rates with the use of increased OS and whether chemotherapy rates have decreased over time.