Comparative performance of breast cancer human epidermal growth factor receptor 2 fluorescence in situ hybridization and brightfield in situ hybridization on college of American pathologists proficiency tests

Katherine B. Geiersbach, Julia A. Bridge, Michelle Dolan, Lawrence J Jennings, Diane L. Persons, Rhona J. Souers, Karen D. Tsuchiya, Patricia H. Vasalos, Joel T. Moncur*

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Context. - Fluorescence in situ hybridization (FISH) and brightfield in situ hybridization (ISH) are 2 clinically approved laboratory methods for detecting ERBB2 (HER2) amplification in breast cancer. Objective. - To compare the performance of FISH and brightfield ISH on proficiency testing administered by the College of American Pathologists Laboratory Accreditation Program. Design. - Retrospective review was performed on 70 tissue core samples in 7 separate proficiency testing surveys conducted between 2009 and 2013. Results. - The samples included 13 consensus-amplified tissue cores, 53 consensus-nonamplified cores, and 4 cores that did not reach consensus for FISH and/or brightfield ISH. There were 2552 individual responses for FISH and 1871 individual responses for brightfield ISH. Consensus response rates were comparable for FISH (2474 of 2524; 98.0%) and brightfield ISH (2135 of 2189; 97.5%). The FISH analysis yielded an average HER2 copy number per cell that was significantly higher (by 2.86; P=.02) compared with brightfield ISH for amplified cores. For nonamplified cores, FISH yielded slightly, but not significantly, higher (by 0.17; P = .10) HER2 copy numbers per cell. There was no significant difference in the average HER2 to control ratio for either consensusamplified or consensus-nonamplified cores. Participants reported "unable to analyze" more frequently for brightfield ISH (244 of 2453; 9.9%) than they did for FISH (160 of 2684; 6.0%). Conclusions. - Our study indicates a high concordance rate in proficiency testing surveys, with some significant differences noted in the technical performance of these assays. In borderline cases, updated American Society of Clinical Oncology/College of American Pathologists cutoff thresholds that place greater emphasis on HER2 copy number per cell could accentuate those differences between FISH and brightfield ISH.

Original languageEnglish (US)
Pages (from-to)1254-1259
Number of pages6
JournalArchives of Pathology and Laboratory Medicine
Volume142
Issue number10
DOIs
StatePublished - Oct 2018

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Medical Laboratory Technology

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