Expanding criteria for prognostic stage IA disease in HR+ breast cancer.

Abstract

550 Background: The 8th ed AJCC staging system incorporated grade, receptor status and the Oncotype DX Recurrence Score (RS) result into staging. Based on TAILORx trial data and evidence of utility for RS results in node positive disease, this study was undertaken to determine if staging should incorporate expanded RS criteria. Methods: Patients (pts) with T1-3N0-3 HR+HER2- disease undergoing surgery 2010-15 were identified in the SEER database. 5yr DSS was estimated based on T and N category, grade and RS result; differences were compared between pts with path prognostic stage IA disease and all other groups. Results: 154,054 pts were identified; median follow up was 49 mo (range 0-83). RS results were obtained in 60,886 (39.5%); RS <11 in 13,570 (22.3%) and RS 11-25 in 39,240 (64.5%). The table details 5yr DSS rates. 5yr DSS for path prognostic stage IA pts (n=114,675, 73.4%) was 98.2%. Among all pts with RS <11, 5yr DSS was excellent and not significantly different than for path prognostic stage IA pts. For those with RS 11-25 not receiving chemo, 5yr DSS was inferior to path prognostic stage IA disease for T1-2N1 pts and for those with T2-3N0 disease although among N0 pts the differences were numerically small (1.4%-2.5% vs overall path prognostic stage IA). Conclusions: Pts with Recurrence Score <11 have excellent 5yr DSS regardless of T and N category or grade suggesting further modification of the AJCC staging system using this cutoff. Additional study is required to optimize staging for patients with Recurrence Score 11-25. [Table: see text]