Molecular characteristics and prognosis of breast cancer patients with different level of HER2 positivity after adjuvant and neoadjuvant chemotherapy.

Abstract

HER2-low breast cancer (BC) has renewed interests of researchers worldwide. Here, we aimed to investigate the clinicopathological characteristics of patients with HER2-low, HER2-0 and HER2 ultra-low BC and make conclusion. We collected cases of patients who were diagnosed as BC at Jingling General hospital. Immunohistochemistry was used to redefine HER2 scores. Kaplan-Meier methods and Cox proportional hazards regression analysis were used to compare survival. We found that HER2-low BC was more frequent in hormone receptor (HR)-positive BC patients and was associated with fewer T3-T4, lower breast conserving surgery rate and higher adjuvant chemotherapy rate. HER2-low BC patients had better overall survival (OS) compared to HER2-0 BC in premenopausal and stage II BC. Furthermore, HER2-0 BC patients had lower Ki-67 expression levels compared to HER2-ultra low and HER2-low BC in HR-negative BC. HER2-0 BC patients also had worse OS rate compared to those with HER2-ultra low BC in HR-positive BC. Finally, HER2-0 BC patients showed a higher pathological response rate compared to those with HER2-low BC after neoadjuvant chemotherapy. These findings suggest that HER2-low BC has distinct biology and clinical features compared to HER2-0 BC, and more investigation is needed to understand the biology of HER2-ultra low BC.