ĐẶC ĐIỂM MÔ BỆNH HỌC VÀ HOÁ MÔ MIỄN DỊCH CỦA UNG THƯ BIỂU MÔ TUYẾN VÚ XÂM NHẬP BỘC LỘ HER2 THẤP

Abstract

Introduction: Recently, the advent of antibody-drug conjugates has shown efficacy in the HER2-low invasive breast carcinoma group, which previously did not respond to trastuzumab monotherapy. However, there is still much debate about whether this constitutes a distinct molecular subgroup. Objective: To describe histopathological and immunohistochemical characteristics of HER2-low invasive breast carcinoma. Methods: A cross-sectional descriptive study was conducted on 314 patients diagnosed with invasive breast carcinoma from surgical specimens at K Hospital from August 2023 to August 2024. Results: The most common histopathological type of HER2-low invasive breast carcinoma was invasive carcinoma of no special type (93.7%). The most frequent histological grade was grade II (75.8%). The rates of lymphovascular invasion and perineural invasion were 14.0% and 5.1%, respectively. The rate of lymph node metastasis was 33.4%. Tumors commonly had an intermediate Nottingham Prognostic Index (NPI), accounting for 52.9%. The rates of ER and PR positivity were 90.4% and 86.4%, respectively. The rates of low and high Ki-67 expression were 40.8% and 59.2%, respectively. The Luminal B/HER2-negative molecular subtype was the most common, at a rate of 56.1%. Conclusion: HER2-low invasive breast carcinoma is predominantly of the no special type, with histological grade II, positive hormone receptors, and a high Ki-67 index. These characteristics correspond to the Luminal B molecular subtype, a group with a higher risk of recurrence after endocrine therapy. The accurate identification of HER2-low status is therefore critically important, as it opens up a highly effective treatment option with new-generation antibody-drug conjugates.