title: Hybridization for human epidermal growth factor receptor 2 testing in gastric carcinoma: a comparison of fluorescence in-situ hybridization with a novel fully automated dual-colour silver in-situ hybridization method.
abstract: OBJECTIVE
  Amplification of the human epidermal growth factor receptor 2 (HER2) gene has been reported in gastric carcinoma (GC). Accordingly, trastuzumab plus chemotherapy has recently become the new standard treatment for HER2-positive advanced GCs. The aim was to compare the alleged gold standard for hybridization [fluorescence in-situ hybridization (FISH)] with a novel, fully automated brightfield dual-colour silver-enhanced in-situ hybridization (SISH) method.
  
  
  RESULTS
  The studies series was comprised of 166 GC samples. Additionally, tumours with discordant results obtained by FISH and SISH were analysed by real-time quantitative polymerase chain reaction (PCR) with the LightMix kit HER-2/neu. Of the samples, 17.5% and 21% were amplified by FISH and SISH, respectively. Heterogeneity was identified in up to 52% of cases. In 96.4% of cases, FISH showed the same results as SISH. All six discordant cases were positive by SISH and negative by FISH. On review of the FISH slides, all contradictory cases were polysomic and were confirmed to be negative for amplification by real-time PCR. Interestingly, all ratios in this latter group were between 2.06 and 2.50, so setting the cut-off for amplification at ≥3 resulted in perfect concordance.
  
  
  CONCLUSIONS
  Dual-colour SISH represents a novel method for the determination of HER2 status in GC.
authors.affiliation: Laboratorio de Dianas Terapeuticas, Centro Integral Oncologico Clara Campal, Hospital Universitario Madrid Sanchinarro, C ⁄ On˜a, 10. 28050 Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: García-García
authors.forename: Carlos
authors.initials: C
authors.lastname: Gómez-Martín
authors.forename: Bárbara
authors.initials: B
authors.lastname: Angulo
authors.forename: Esther
authors.initials: E
authors.lastname: Conde
authors.forename: Ana
authors.initials: A
authors.lastname: Suárez-Gauthier
authors.forename: Magdalena
authors.initials: M
authors.lastname: Adrados
authors.forename: Cristian
authors.initials: C
authors.lastname: Perna
authors.forename: José Luis
authors.initials: JL
authors.lastname: Rodríguez-Peralto
authors.forename: Manuel
authors.initials: M
authors.lastname: Hidalgo
authors.forename: Fernando
authors.initials: F
authors.lastname: López-Ríos
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics; D057205:Automation, Laboratory / Q000379:methods; D005784:Gene Amplification; D018628:Gene Dosage; D018734:Genes, erbB-2; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods* / Q000592:standards; D017404:In Situ Hybridization, Fluorescence / Q000379:methods* / Q000592:standards; D060888:Real-Time Polymerase Chain Reaction; D012834:Silver; D013274:Stomach Neoplasms / Q000235:genetics*
chemical_list: D012834:Silver