Clinicopathological characteristics and value of HER2-low expression evolution in breast cancer receiving neoadjuvant chemotherapy.

Objective: The present study aimed to evaluate the clinicopathological characteristics and value of HER2-low expression evolution in breast cancer receiving neoadjuvant chemotherapy (NAC).
Methods: Patients with HER2 negative breast cancer receiving NAC from January 2017 to December 2020 were enrolled in this study. The clinicopathological characteristics, response to NAC, evolution of HER2 and prognostic value were retrospectively analyzed.
Results: 410 patients were included. The proportion of HR positive disease in HER2-low cases was higher than in HER2-zero population (75.8 % vs. 65.8 %, P = 0.040). No statistical significant difference in pCR rate was observed between HER2-low and HER2-zero patients (33.8 % vs. 39.3 %, P = 0.290) when pCR was defined as ypTis/0ypN0. Exploratory analysis revealed that the pCR rate of HER2-low cases was significantly lower than HER2-zero patients in the entire population (19.8 % vs. 33.3 %, P = 0.004) and HR positive population (12.6 % vs. 29.9 %, P = 0.001) when pCR was defined as ypT0ypN0. The evolution rate of HER2 expression after NAC was 31.0 % in HER2-zero patients and 24.7 % in HER2-low patients. Compared with patients with HR positive disease, patients with TNBC had higher evolution rate of HER2 expression after NAC (37.7 % vs. 23.6 %). Significant association was observed between HER2 evolution with histology type and Ki-67 index in HER2-zero patients and with lymph node involvement, HR status and Ki-67 index in HER2-low patients. Prognostic impact of HER2 evolution was not observed.
Conclusions: HR positive and HR negative HER2-low breast cancer exhibit different clinicopathological features, response to NAC and HER2 evolution after treatment.
Competing Interests: Declaration of competing interest The authors declare that no potential conflict of interest exist.
(Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)