title: Prospective multi-centre study to validate chromogenic in situ hybridisation for the assessment of HER2 gene amplification in specimens from adjuvant and metastatic breast cancer patients.
abstract: OBJECTIVE
  As HER2 status is a strong predictor of the response to trastuzumab, clinical guidelines recommend that all breast tumours are first evaluated for HER2 protein expression by immunohistochemistry (IHC) followed by confirmatory testing for HER2 gene amplification using fluorescence in situ hybridisation (FISH) for 2+ cases. Alternatively, chromogenic in situ hybridisation (CISH) offers a simpler, less expensive approach to detect HER2 amplification.
  
  
  METHODS
  In this prospective, multi-centre study, based on the largest dataset for HER2 testing in Germany to date, we evaluated the concordance between FISH and CISH in 399 samples from adjuvant and metastatic breast cancer patients. Tumour specimens from routine diagnostic practice were analysed by IHC, FISH and CISH in four reference centres.
  
  
  RESULTS
  FISH and CISH results were strongly concordant (κ = 0.83), with 95% of cases showing agreement. Despite variable IHC scoring across testing centres, complete consensus among the three methods was observed for 246 cases, representing 91% of all IHC positive (3+) or negative (0/1+) cases. Confirmatory testing of 132 IHC equivocal (2+) cases also yielded highly concordant results between FISH and CISH.
  
  
  CONCLUSIONS
  These data validate CISH for the assessment of HER2 gene amplification in breast tumours and, confirm CISH as a valid alternative to FISH in HER2 testing.
authors.affiliation: Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Riethdorf
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hoegel
authors.forename: Birgit
authors.initials: B
authors.lastname: John
authors.forename: German
authors.initials: G
authors.lastname: Ott
authors.forename: Peter
authors.initials: P
authors.lastname: Fritz
authors.forename: Susanne
authors.initials: S
authors.lastname: Thon
authors.forename: Thomas
authors.initials: T
authors.lastname: Loening
authors.forename: Klaus
authors.initials: K
authors.lastname: Pantel
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D001943:Breast Neoplasms / Q000737:chemistry* / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D002863:Chromogenic Compounds; D005260:Female; D018734:Genes, erbB-2; D005858:Germany; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization / Q000379:methods; D017404:In Situ Hybridization, Fluorescence; D008875:Middle Aged; D021141:Nucleic Acid Amplification Techniques / Q000379:methods; D011446:Prospective Studies; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D002863:Chromogenic Compounds; D000068878:Trastuzumab
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