Clinical Outcomes In Er+Her2-Negative Breast Cancer (Bc) Where Treatment Decisions Incorporated The 21-Gene Recurrence Score (Rs): Elderly (>= 70 Yrs) Vs Younger Patients (Pts).

543Background: Elderly BC pts are generally undertreated, despite evidence suggesting that they may benefit from adjuvant chemotherapy (CT). We compared treatments/clinical outcomes in elderly vs younger Clalit Health Services (CHS) pts undergoing RS testing. Methods: This exploratory analysis of the CHS registry included BC pts with N0/N1mi/N1 disease who were RS-tested from 1/2006 (CHS approval of the test) through 12/2010 (N0) or 12/2011 (N1mi/N1). Medical records were reviewed to verify treatments/recurrences/survival. Results: The analysis included 458 elderly and 2052 younger pts, with a median (range) follow-up of 5.7 (0.9-9.6) and 6.1 (0.1-10.3) yrs, respectively. In the elderly/younger pts, median age was 73/58 yrs, 48%/52% had grade 2 tumors, median tumor size was 1.6/1.5 cm, 70%/72% were N0 and 30%/28% were N1mi/N1. RS distribution (u003c18, 18-30, ≥31) among elderly pts was 56%, 33%, and 11%, respectively, compared to 49%, 41%, and 10%, respectively, in younger pts. In pts with RS 18-30 and RS≥31,...