title: Comparison of Pathvysion and Poseidon HER2 FISH assays in measuring HER2 amplification in breast cancer: a validation study.
abstract: OBJECTIVE
  The current study was done as a validation study prior to setting up a clinical HER2 testing service using the new commercial Poseidon HER2 fluorescence in situ hybridisation (FISH) assay. However, it was felt that the experience of the authors of this study may be of interest to other laboratories when considering setting up a HER2 diagnostic facility.
  
  
  METHODS
  122 patients who had been diagnosed with invasive breast cancer were selected. Immunolabelling with HercepTest, PathVysion and Poseidon FISH assays were carried out using tissue microarray blocks.
  
  
  RESULTS
  Concordance correlation coefficients showed near perfect agreement in average HER2 and centromere specific signal counts per cell and in the HER2/CEP17 ratios between the PathVysion and the Poseidon FISH assays. In addition, the kappa measure showed perfect agreement (kappa 0.9441, p<0.0001), and if only 2+ cases were considered there was substantial agreement (kappa 0.7671, p=0.0006), between the two assays. The sensitivity and the specificity of the Poseidon FISH kit were calculated to be 95.2% and 100%, respectively, whereas the positive predictive value (PPV) and negative predictive value (NPV) were 100% and 99%, respectively. With regard to the ability to presume HER2 polysomy, the Poseidon FISH kit had a sensitivity of 93.3% and a specificity of 99.1%, with PPV and NPV of 93.3% and 99.1%, respectively, as assessed with PathVysion classification as the reference.
  
  
  CONCLUSIONS
  Statistical analysis confirmed that the two FISH assays are comparable in terms of detection of HER2 gene amplification. Proceeding from these findings, the genetic diagnoses obtained with the Poseidon kit can be considered to be as valuable as the results from the Food and Drug Administration approved PathVysion assay, and its utilisation in routine HER2 diagnostics is proposed.
authors: Department of Pathology, Josa Andras County Hospital, H-4400Nyiregyhaza, Hungary.
authors: Monika
authors: M
authors: Francz
authors: Kristof
authors: K
authors: Egervari
authors: Laszlo
authors: L
authors: Kardos
authors: Judit
authors: J
authors: Toth
authors: Zoltan
authors: Z
authors: Nemes
authors: Janos
authors: J
authors: Szanto
authors: Zoltan
authors: Z
authors: Szollosi
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D004812:Epidemiologic Methods; D005260:Female; D005784:Gene Amplification; D018734:Genes, erbB-2; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D009361:Neoplasm Invasiveness; D011933:Reagent Kits, Diagnostic; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis* / Q000235:genetics; D046888:Tissue Array Analysis / Q000379:methods
chemical_list: D011933:Reagent Kits, Diagnostic; D018719:Erb-b2 Receptor Tyrosine Kinases