title: Testing HER2 in breast cancer: a comparative study on BRISH, FISH, and IHC.
abstract: New brightfield in-situ hybridization (BRISH) methods based on the cohybridization of probes to the HER2 gene and chromosome 17 centromere have been developed and provide a promising alternative to fluorescence in-situ hybridization (FISH). The aim of this correlation study was to test HER2 status in primary breast carcinomas with 2 BRISH methods, FISH, and 2 immunohistochemical assays using tissue microarray technology.
  
  
  METHODS
  Tissue cores (1.5 mm) were collected from 218 consecutive, archival formalin-fixed paraffin-embedded primary breast carcinomas into 4 duplicate tissue microarrays. Tumor tissue samples from 201 patients were successfully prepared in all 5 investigated methods comprising DuoCISH (Dako), Dual ISH (Ventana), HER-2 pharmDxFISH (Dako), HercepTest (Dako), and PATHWAY (4B5; Ventana).
  
  
  RESULTS
  In this study the overall agreement between Dual ISH and FISH was 98.5% with a specificity of 99% and a sensitivity of 96%. DuoCISH had an equivalent high-positive agreement with FISH (sensitivity of 96%), but a lower specificity of 93% and an overall agreement of 93% with FISH. The overall agreement between the 2 immunohistochemical methods and FISH was almost perfect (Dako HercepTest 97% and Ventana PATHWAY (4B5) 98%). With regard to specificity the 2 methods performed equally (99.4%).
  
  
  CONCLUSIONS
  BRISH methods provide an alternative to FISH in evaluating HER2/CEN17 ratio in primary breast carcinomas. Dual ISH showed an almost perfect agreement with FISH and is a fast track method realistic to perform on all breast carcinomas. BRISH provide a permanent result that makes the method eligible for use in internal and external quality assurance.
authors.affiliation: Department of Pathology, Aalborg Hospital †Department of Pathology, Aarhus Hospital, Aarhus University Hospital. ahb@rn.dk
authors.forename: Anja
authors.initials: A
authors.lastname: Brügmann
authors.forename: Giedrius
authors.initials: G
authors.lastname: Lelkaitis
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
authors.forename: Kirsten Gadgaard
authors.initials: KG
authors.lastname: Jensen
authors.forename: Vibeke
authors.initials: V
authors.lastname: Jensen
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D002503:Centromere / Q000235:genetics / Q000378:metabolism*; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics; D005260:Female; D018734:Genes, erbB-2 / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization / Q000379:methods; D008875:Middle Aged; D009367:Neoplasm Staging; D015588:Observer Variation; D012680:Sensitivity and Specificity