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Original Article
Clinicopathological Features and Long-Term Prognostic Role of Human Epidermal Growth Factor Receptor-2 Low Expression in Chinese Patients with Early Breast Cancer: A Single-Institution Study
KONG Zi Qing, LIU Li Qun, HUANG De Qin, WANG Yu Tong, LI Jing Jie, ZHANG Zheng, WANG Xi Xi, LIU Chuan Ling, ZHANG Ya Di, SHAO Jia Kang, ZHU Yi Min, CHEN Yi Meng, LIU Mei, ZHAO Wei Hong
, Available online  , doi: 10.3967/bes2024.014
  Objective   This study aimed to comprehensively analyze and compare the clinicopathological features and prognosis of Chinese patients with human epidermal growth factor receptor 2 (HER2)-low early breast cancer (BC) and HER2-IHC0 BC.  Methods   Patients diagnosed with HER2-negative BC (N = 999) at our institution between January 2011 and December 2015 formed our study population. Clinicopathological characteristics, association between estrogen receptor (ER) expression and HER2-low, and evolution of HER2 immunohistochemical (IHC) score were assessed. Kaplan-Meier method and log-rank test were used to compare the long-term survival outcomes (5-year follow-up) between the HER2-IHC0 and HER2-low groups.  Results   HER2-low BC group tended to demonstrate high expression of ER and more progesterone receptor (PgR) positivity than HER2-IHC0 BC group (P < 0.001). The rate of HER2-low status increased with increasing ER expression levels (Mantel-Haenszel χ2 test, P < 0.001, Pearson’s R = 0.159, P < 0.001). Survival analysis revealed a significantly longer overall survival (OS) in HER2-low BC group than in HER2-IHC0 group (P = 0.007) in the whole cohort and the hormone receptor (HR)-negative group. There were no significant differences between the two groups in terms of disease-free survival (DFS). The discordance rate of HER2 IHC scores between primary and metastatic sites was 36.84%.  Conclusion   HER2-low BC may not be regarded as a unique BC group in this population-based study due to similar clinicopathological features and prognostic roles.