HER2 positive breast cancer patients having HER2 loss after neoadjuvant chemotherapy should still be treated with adjuvant anti-HER2 treatment

Abstract

I want to congratulate Robertson and their colleagues for their article [1] in which they investigated the concordance of biomarkers and immunohistochemical (IHC)-based surrogate tumor subtypes between core needle biopsies (CNB) and consecutive paired breast cancer surgical resections. This retrospective study comprised two cohorts of patients with primary breast cancer: one treated with primary surgery (n = 526) and one with neoadjuvant chemotherapy (NAC) (n = 216). They reported that the agreement of HER2 and Ki67 between CNB and paired surgical specimen in primary breast cancer is insufficient. In the NAC cohort, 10 tumors were HER2 positive on CNB but lost either HER2 expression and/or gene amplification after NAC. The authors concluded that re-testing of at least HER2 and Ki67 should be considered to optimize tailored adjuvant therapy especially for patients treated with NAC. HER2 discordance might be related to intra-tumoral heterogeneity. In current clinical practice, it is common question that whether patients with HER2 loss after NAC should be still treated with adjuvant anti-HER2 treatment or not. Relying on the fact that these tumors were HER2 positive at the time of the initial diagnosis, such patients should still be treated with HER2-targeted therapy during adjuvant treatment [2]. Funding No funding for this paper.