How is the clinical value of HER2-low expression in early breast cancer with the neoadjuvant setting: an ambidirectional cohort study.

Abstract

Background: Cumulative studies supported that HER2 low is a biological subtype of breast cancer however controversial conclusions were made in different real-world studies. We explored the differences in clinical characteristics and short-term and long-term prognosis outcomes between HER2 0 and HER2 low early breast cancer patients using an ambidirectional cohort in China. Methods: Among 711 patients who first diagnosed with breast cancer between January 1, 2016 to December 31, 2020, those with neoadjuvant chemotherapy were screened. Finally, 303 patients were included in our analysis and 90 patients (29.7%) with HER2 = 0 and 213 patients (70.3%) with HER2 = 1+. Propensity score method with inverse probability of treatment weighting was applied to account for the confounders. Results from weighted Kaplan-Meier curve and log-rank test, weighted logistic and cox regression were used to compare two groups. Results: Regarding the baseline and clinical characteristics between HER2-low and HER2-0 group. Family history of caner, ER, PR, HR, Ki-67 labeling index and treatment regimens were observed different. 35% patients used EC-T/EC-P/AC-P treatment. Regarding the bpCR, ORR and rwOS, after multivariate adjustment and propensity score method, no evidence indicated any differences between two groups. Conclusions: HER2-low as a specific biological subtype remains difficult. The HER2-low expression can differ from the therapeutic value in neoadjuvant setting among early breast cancer patients. Further research on the understanding of HER2 low breast cancer is necessary.