Using Oncotype DX Breast Recurrence Score® Assay to Define the Role of Neoadjuvant Endocrine Therapy in Early-Stage Hormone Receptor-Positive Breast Cancer

Abstract Purpose The role of neoadjuvant endocrine therapy in the treatment of patients with early stage, hormone receptor-positive (HR+) breast cancer is not well defined. During the early part of the COVID-19 pandemic, neoadjuvant endocrine therapy was used more commonly by physicians in an attempt to delay surgery and possible exposure to COVID-19 during hospitalization; this change raised important questions surrounding the use of neoadjuvant endocrine therapy. Methods We assessed the rate of clinical and pathologic complete response (cCR, pCR) among a pooled cohort of patients with early stage HR + breast cancer who had been randomized to neoadjuvant endocrine therapy or neoadjuvant chemotherapy in two earlier studies to understand better how outcomes varied by Oncotype DX Breast Recurrence Score® assay. Results We observed that patients with intermediate RS results had no statistically significant differences in pathologic outcomes at the time of surgery based on whether they received neoadjuvant endocrine therapy or neoadjuvant chemotherapy, suggesting that a subgroup of women with a RS 0–25 may omit chemotherapy without compromising outcomes. Conclusion These data suggest that Recurrence Score® (RS) results may serve as a useful tool in treatment decision-making in the neoadjuvant setting.