Abstract PS3-10-12: Adjuvant chemotherapy and anthracycline use in older adults with high oncotype DX scores: A SEER-Medicare analysis

Abstract Background: Determining what adjuvant chemotherapy regimen to select in older patients with higher-risk, early-stage hormone receptor (HR)+, human epidermal growth factor receptor 2 (HER2)- breast cancers can be challenging. Patients with early-stage HR+/HER2-, node-negative breast cancer with high Oncotype DX recurrence scores (>31) may benefit from the addition of anthracyclines (1). However, it is not known whether this is true for older patients. The purpose of this study was to investigate outcomes based on Oncotype DX score and type of adjuvant treatment among older patients with early-stage, HR+/HER2- breast cancer using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Methods: Using the SEER-Medicare database, we identified 5,439 women aged 66 years and older with a diagnosis of Stage I-III HR+/HER2- breast cancer between 2000 and 2019, and who had a recorded Oncotype DX score. We assessed patient characteristics, type of therapy received (anthracycline+taxane-based chemotherapy, taxane-based chemotherapy, or endocrine therapy), and Oncotype DX recurrence score (low [