HER2 Testing: How to Reach a High Concordance Rate between Immunohistochemistry and Fluorescence in Situ Hybridization

Thaer Khoury*, Swati Kulkarni, Carl Morrison, Wiam Bshara, Yousef Zakharia, Stephen Edge

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Background: The concordance rate between immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for human epidermal growth factor receptor-2 (HER2) is still a major clinical concern. We describe a new criteria evaluating HER2 IHC. Materials and Methods: We expanded the equivocal category to include the American Society of Clinical Oncology and College of American Pathologists equivocal category and cases with 3+ between 30% to 90% of tumor cells and 2+ in 1% of tumor cells. Then, we prospectively evaluated 106 cases with FISH. Results: There were 2 categories that were not required to be tested by FISH based on American Society of Clinical Oncology and College of American Pathologists criteria. The first category, cases with 2+staining between 1% and <10%. In this category, there were 15 cases, 2 (13.3%) had HER2 amplification by FISH. The second category, cases with 3+ staining between 30% and 90%. In this category, there were 16 cases, 5 (31.3%) were not amplified and 1 (6.3%) was borderline. Conclusions: Expanding the equivocal category could increase the concordance rate between IHC and FISH with minimal additional cost.

Original languageEnglish (US)
Pages (from-to)424-430
Number of pages7
JournalApplied Immunohistochemistry and Molecular Morphology
Volume19
Issue number5
DOIs
StatePublished - Oct 1 2011

Keywords

  • concordance
  • fluorescence in situ hybridization
  • immunohistochemistry

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Medical Laboratory Technology

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