Abstract P5-20-12: Adjuvant DCH vs TCH for low-risk (node negative); and FECDH vs TCH for high-risk (node positive) HER2+ breast cancer – A retrospective provincial analysis

Background: Chemotherapy plus trastuzumab for early HER2+ breast cancer (BC) is associated with improved survival. Optimal regimens for low-risk (node negative) and high-risk (node positive) HER2+ breast cancers are unknown and choice of regimen varies in real-world clinical practice. Objective: (1) For low-risk breast cancer, to compare DCH (4 cycles) and TCH (6 cycles) in terms of disease free (DFS) and overall survival (OS). (2) For high-risk breast cancer, to compare FECDH (6 cycles) and TCH (6 cycles) in terms of DFS and OS. Methods: All women diagnosed from 2007-2014 with stage I-III, hormone receptor (HR) +/-, HER2+ BC receiving adjuvant chemotherapy plus trastuzumab (n=986) in Alberta, Canada were included. Patients with low-risk (node negative) disease were stratified into DCH (n=104) or TCH (n=360) cohorts for DFS/OS comparison (Kaplan-Meier). Patients with high-risk (node positive) disease were stratified into FECDH (n=145) or TCH (n=314) cohorts. Subgroup analysis of the high-risk cohorts by HR+/HER2+ and HR-/HER2+ for FECDH vs TCH were performed. Chi-square was used to evaluate for difference between cohort variables. Results: Median follow-up was 58.1 months in the low-risk cohort and 63.1 months in the high-risk cohort. In the low-risk group, patients receiving TCH had more mastectomy (69.5%) than lumpectomy (30.5%; p Conclusion: In low-risk HER2+ BC, 4 cycles of DCH chemotherapy has high survival with similar outcomes to 6 cycles of TCH. In high-risk HER2+ BC, FECDH has comparable outcomes to TCH consistent with BCIRG-006. This study suggests that women with HR+/HER2+ breast cancer have improved OS with anthracycline containing regimens, such as FECDH. Although non-significant, patients with HR-/HER2+ BC may have some improvement in DFS and OS with TCH, a carboplatin containing regimen. Citation Format: Veitch ZW, Khan OF, Tilley D, Kostaras X, Tang PA, King K, Lupichuk S. Adjuvant DCH vs TCH for low-risk (node negative); and FECDH vs TCH for high-risk (node positive) HER2+ breast cancer – A retrospective provincial analysis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-20-12.