Significance of HER2 in Microinvasive Breast Carcinoma

Abstract Objectives We compared the clinicopathologic features, clinical management, and outcomes of human epidermal growth factor receptor 2 (HER2)–expressing nonexpressing microinvasive breast carcinomas (MiBC) to explore significance HER2 in MiBC. Methods Clinicopathologic follow-up information cases with final diagnosis MiBC known status between 2007 2019 were analyzed. Results Nineteen (41.3%) HER2-positive (HER2+) 27 (58.7%) HER2-negative (HER2?) MiBCs identified. positivity was likely be associated high nuclear grade, presence tumor-infiltrating lymphocytes, hormonal negativity, increased Ki-67 both situ carcinomas. Nodal metastases found ER+/HER2? (5.3%). One HER2+ case have isolated tumor cells axillary node. The majority patients (76.5%) did not receive HER2-targeted therapy. All available alive without recurrence or distant metastasis, a median 38 months. Conclusions Similar larger size invasive carcinomas, is high-grade morphologic features MiBCs. However, overexpression does appear nodal metastasis worse outcome our study cohort. role therapy this setting merits additional study.