A Comparative Analysis of HER2 Immunohistochemistry in Core Biopsy Versus Excision in the Era of HER2 ``Low'' Breast Cancers

IF 2.7 3区医学 Q2 ONCOLOGY

Clinical breast cancer Pub Date : 2026-03-01 Epub Date: 2026-01-16 DOI:10.1016/j.clbc.2025.11.016

Swati Bhardwaj , Shabnam Jaffer

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Abstract

Background

The Destiny B04 trial led to the recognition of HER2 low as a new entity defined as HER2 immunohistochemistry (IHC) score of 1 +/2 + and negative in situ hybridization (ISH) requiring detailed HER2 IHC scoring (negative = 0 & 1 +, equivocal = 2 +, and positive = 3 +). As per ASCO–CAP guidelines, biomarkers need not be repeated on excisions when done on core biopsy with some exceptions. The goal of our study was to compare the concordance of HER2 low between core biopsies and excisions and assess the need to repeat on excision.

Methods

At the study institution biomarkers are first performed on core biopsies and then repeated on all excisions in negative cases. We identified 301 cases of primary breast carcinomas with matched HER2 IHC on core biopsies and excisions. We reviewed and scored all HER2 IHC slides as per 2018 ASCO/CAP guidelines.

Results

The incidence of HER2 low on core biopsies decreased from 64% to 46% on excisions. The best concordance was seen in HER2 + (82%) and negative cases (84%), with most variability in predominantly 1 + and some 2 + cases in both directions. There was a greater loss (38%) than gain (16%) in HER2 low values from core biopsy to excision.

Conclusions

HER2 low discordance in our series was predominantly due to loss from core biopsies to excisions, which maybe attributed to better meeting the pre analytic criteria on core biopsy. In contrast, the gain maybe due to intratumoral heterogeneity and or interobserver variability and despite low, worth repeating HER2 IHC on excisions in negative cases.

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HER2“低”乳腺癌时代核心活检与切除HER2免疫组化的比较分析

背景：Destiny B04试验将HER2 low定义为一个新的实体，定义为HER2免疫组织化学（IHC）评分为1 +/2 +，而原位杂交（ISH）阴性需要详细的HER2 IHC评分（阴性= 0 + 1 +，模棱两可= 2 +，阳性= 3 +）。根据ASCO-CAP指南，除了一些例外，在核心活检中切除时不需要重复生物标志物。我们研究的目的是比较核心活检和切除之间HER2低的一致性，并评估是否需要重复切除。方法：在研究机构，首先对核心活检进行生物标记，然后对阴性病例的所有切除重复进行生物标记。我们确定了301例原发性乳腺癌，核心活检和切除术中HER2 IHC匹配。我们根据2018年ASCO/CAP指南对所有HER2 IHC载玻片进行了审查和评分。结果：核心活检中HER2低的发生率从64%下降到46%。在HER2 +(82%)和阴性病例（84%）中发现了最好的一致性，在两个方向上主要是1 +和一些2 +病例的变异。从核心活检到切除，HER2低值的损失（38%）大于增加（16%）。结论：在我们的研究中，HER2低差异主要是由于核心活检的丢失而导致的切除，这可能是由于更好地满足核心活检的分析前标准。相比之下，这种增加可能是由于肿瘤内的异质性和/或观察者之间的可变性，尽管在阴性病例中切除的HER2 IHC很低，但值得重复。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Clinical breast cancer 医学-肿瘤学

CiteScore

5.40

自引率

3.20%

发文量

174

审稿时长

48 days

期刊介绍： Clinical Breast Cancer is a peer-reviewed bimonthly journal that publishes original articles describing various aspects of clinical and translational research of breast cancer. Clinical Breast Cancer is devoted to articles on detection, diagnosis, prevention, and treatment of breast cancer. The main emphasis is on recent scientific developments in all areas related to breast cancer. Specific areas of interest include clinical research reports from various therapeutic modalities, cancer genetics, drug sensitivity and resistance, novel imaging, tumor genomics, biomarkers, and chemoprevention strategies.