Human epidermal growth factor receptor 2 (HER2) status in breast cancer: practice points and challenges

Histopathology. 2024 Sep;85(3):371-382. doi: 10.1111/his.15213. Epub 2024 Jun 6.

Abstract

Human epidermal growth factor receptor 2 (HER2)-enriched breast cancer benefits significantly from anti-HER2 targeted therapies. This highlights the critical need for precise HER2 immunohistochemistry (IHC) interpretation serving as a triage tool for selecting patients for anti-HER2 regimens. Recently, the emerging eligibility of patients with HER2-low breast cancers for a novel HER2-targeted antibody-drug conjugate (T-DXd) adds challenges to HER2 IHC scoring interpretation, notably in the 0-1+ range, which shows high interobserver and interlaboratory staining platform variability. In this review, we navigate evolving challenges and suggest practical recommendations for HER2 IHC interpretation.

Keywords: HER2; HER2 scoring; HER2‐low; breast cancer.

Publication types

  • Review

MeSH terms

  • Biomarkers, Tumor* / analysis
  • Biomarkers, Tumor* / metabolism
  • Breast Neoplasms* / diagnosis
  • Breast Neoplasms* / metabolism
  • Breast Neoplasms* / pathology
  • Female
  • Humans
  • Immunohistochemistry* / methods
  • Receptor, ErbB-2* / analysis
  • Receptor, ErbB-2* / metabolism

Substances

  • Receptor, ErbB-2
  • ERBB2 protein, human
  • Biomarkers, Tumor