Abstract P5-09-04: Efficacy of neoadjuvant endocrine therapy compared with neoadjuvant chemotherapy in pre-menopausal patients with hormone-responsive and HER2-negative, lymph node-negative breast cancer

Abstract Background: Neoadjuvant endocrine therapy (NET) has demonstrated efficacy in post-menopausal patients with hormone-responsive and her2-negative breast cancer. This trial was designed to compare the efficacy of neoadjuvant chemotherapy (NCT) with NET in pre-menopausal patients with hormone-responsive, her2-negative and lymph node-negative breast cancer. Materials and Methods: In this prospective, randomised study, pre-menopausal patients with hormone-responsive, her2-negative and lymph node-negative breast cancer were recruited. Enrolled patients were randomly assigned (1:1) to receive either NCT or NET with goserelin and tamoxifen, followed by goserelin and anastrozole. The primary purpose was to evaluate the non-inferiority of NET compared to NCT using clinical response, assessed by ultrasound. Results: A total of 68 patients were assigned to receive NCT (n = 31) or NET (n = 37). The clinical response rate was 16.1% for NCT and 35.1% for NET (estimated difference19%, 95%CI:-1.1%-39.1%, non-inferior p = 0.002). Rates of breast-conserving surgery were similar between NCT and NET (90.3% vs 83.8%, p=0.494). Conclusions: The clinical response rate of NET is non-inferior to NCT in pre-menopausal patients with hormone-responsive, HER2-negative, lymph node-negative breast cancer. Summary of ultrasound clinical response The breast surgery and MP grading system Citation Format: chongshan gu, yingjian he, jinfeng li, tianfeng wang, zhaoqing Fan, tao ouyang. Efficacy of neoadjuvant endocrine therapy compared with neoadjuvant chemotherapy in pre-menopausal patients with hormone-responsive and HER2-negative, lymph node-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-09-04.