Chiara Corti, Tianyu Li, Alyssa R. Martin, Melissa E. Hughes, Tonia Parker, Tyzaire S. Duporte, Giuseppe Curigliano, Tari A. King, Elizabeth A. Mittendorf, Nancy U. Lin, Nabihah Tayob, Sara M. Tolaney
BACKGROUND: Pathologic complete response (pCR) after neoadjuvant treatment (NAT) is prognostic for recurrence-free survival (RFS) and overall survival (OS) in breast cancer (BC). We assessed prognostic factors for RFS and OS in patients with pCR compared to residual disease (RD) in HER2+ and triple-negative breast cancer (TNBC). METHODS: We retrospectively evaluated patients with early HER2+ BC or TNBC who underwent surgery following NAT at Dana-Farber Cancer Institute and who had data on pCR (ypT0/is, ypN0), RD, RFS, and OS. Clinical tumor size (cT), nodal status (cN), and subtype were assessed using Cox models and Kaplan-Meier methods (p < .05 significant). RESULTS: 863 patients (median age 50.2, range 21.0-85.4) underwent surgery from 2016 to 2021, with a median follow-up of 3.5 years. Three-year RFS was 87% overall, 93% in HER2+, and 80% in TNBC cohorts. Among 374 pCR patients (43.3%), 3-year RFS was 98%, compared to 79% in 489 RD patients (56.7%). In HER2+ BC, 3-year RFS was 99% for pCR vs. 87% for RD, while in TNBC it was 97% for pCR vs. 72% for RD. Higher cT, positive cN, TNBC subtype, and RD were associated with poorer RFS and OS. In pCR, 3-year RFS was numerically higher in cT1-2 compared to cT3-4 and in cN0 compared to cN+ (not significant). In RD, higher cT, positive cN, and TNBC subtype remained associated with poorer outcomes. Multivariate analysis found no associations in pCR patients. CONCLUSION: Patients experiencing pCR had better outcomes. cT, cN, and subtype were prognostic only in patients with RD.