Evidence for Unified Assessment Criteria of HER2 IHC in Colorectal Carcinoma

Authors:

Mark G. Evans 1, Harris B. Krause 1, Andrew Elliott 1, Emil Lou 2, Hassan Ghani 1, Rhonda K. Yantiss 3, Monica T. Garcia-Buitrago 3, Jinru Shia 4, Rona Yaeger 4, Matthew J. Oberley 1, David A. Bryant 1, Jaclyn F. Hechtman 1

Introduction

  • HER2 expression is an important biomarker for the management of RAS wild-type metastatic colorectal carcinoma.
  • Immunohistochemistry (IHC) with reflex in situ hybridization (ISH) is accepted as a standard method of assessment, yet there are currently two sets of criteria used to interpret results: HERACLES criteria: ISH confirmation when IHC staining is 3+ in 10-49% of cells.
  • My Pathway criteria: Do not require ISH confirmation when IHC staining is 3+ in 10-49% of cells.
  • We aimed to assess the prevalence of HER2 3+ heterogeneity and its association with HER2 copy number amplification (CNA).
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