A multicenter study on efficacy of dual-target neoadjuvant therapy for HER2-positive breast cancer and a consistent analysis of efficacy evaluation of neoadjuvant therapy by Miller-Payne and RCB pathological evaluation systems (CSBrS-026).

ABSTRACT

Objective: The aim of this study was to investigate the factors influencing pathological complete response (pCR) rate in early breast cancer patients receiving neoadjuvant dual-target [trastuzumab (H) + pertuzumab (P)] therapy combined with chemotherapy. Additionally, the consistency of the Miller-Payne and residual cancer burden (RCB) systems in evaluating the efficacy of neoadjuvant therapy for early human epidermal growth factor receptor-2 (HER2)+ breast cancer was analyzed. Methods: The clinicopathological data of female patients with early-stage HER2+ breast cancer who received dual-target neoadjuvant therapy at 26 hospitals of the Chinese Society of Breast Surgery (CSBrS) from March 2019 to December 2021 were collected. Patients were allocated to four groups the HER2 immunohistochemistry (IHC) 3+/hormone receptor (HR)-, IHC3+/HR+, IHC2+ in situ hybridization (ISH)+/HR- and IHC2+ ISH+/HR+ groups. The overall pCR rate for patients, the pCR rate in each group and the factors affecting the pCR rate were analyzed. The consistency between the Miller-Payne and RCB systems in assessing the efficacy of neoadjuvant therapy was analyzed. Results: From March 1, 2019, to December 31, 2021, 77,376 female patients with early-stage breast cancer were treated at 26 hospitals; 18,853 (24.4%) of these patients were HER2+. After exclusion of unqualified patients, 2,395 patients who received neoadjuvant dual-target (H+P) therapy combined with chemotherapy were included in this study. The overall pCR rate was 53.0%, and the patients' HR statuses and different HER2+ statuses were significantly correlated with the pCR rate (P<0.05). The consistency of the pathological efficacy assessed by the Miller-Payne and RCB systems was 88.0% (κ=0.717, P<0.001). Conclusions: Different HER2 expression statuses and HR expression statuses are correlated with the pCR rate after dual-target neoadjuvant therapy in HER2+ breast cancer patients. There is a relatively good consistency between Miller-Payne and RCB systems in evaluating the pathologic efficacy of neoadjuvant therapy for HER2+ breast cancer.