title: High concordance between two companion diagnostics tests: a concordance study between the HercepTest and the HER2 FISH pharmDx kit.
abstract: The present study was done to investigate the concordance between the HER2 status measured by immunohistochemical analysis (HercepTest, DAKO, Carpinteria, CA) and fluorescence in situ hybridization (FISH; HER2 FISH pharmDx, DAKO) in a large study cohort (n = 681) of patients with high-risk breast cancer. A high agreement between immunohistochemical and FISH results was demonstrated. For the whole study population, the agreement between the 2 assays was 93.1% with a corresponding κ coefficient of 0.85. When the equivocal immunohistochemical 2+ cases were excluded from the analysis (n = 79), the agreement increased to 95.0% with a κ coefficient of 0.90. When the cutoff value for amplified/nonamplified cases in the HER2 FISH assay was increased from 2.0 to 2.2 as recommended in the American Society of Clinical Oncology/College of American Pathologists guidelines, the concordance between the 2 assays was 94.3% with a κ coefficient of 0.87 in the whole study population. When the equivocal immunohistochemical 2+ cases were excluded from this analysis, the concordance is similar (95.7% with a κ coefficient of 0.91).
authors.affiliation: Dx-Rx Institute, Baunevaenget 76, DK-3480 Fredensborg, Denmark. jan.trost@dx-rx.dk
authors.forename: Jan Trøst
authors.initials: JT
authors.lastname: Jørgensen
authors.forename: Susanne
authors.initials: S
authors.lastname: Møller
authors.forename: Birgitte B
authors.initials: BB
authors.lastname: Rasmussen
authors.forename: Henrik
authors.initials: H
authors.lastname: Winther
authors.forename: Andreas
authors.initials: A
authors.lastname: Schønau
authors.forename: Ann
authors.initials: A
authors.lastname: Knoop
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human