title: Comparison of fluorescence in-situ hybridisation   with dual-colour in-situ hybridisation for   assessment of HER2 gene amplification of breast   cancer in Hong Kong.
abstract: OBJECTIVE
  To compare the PathVysion fluorescence in-situ hybridisation assay with the INFORM HER2 Dual in-situ hybridisation assay on 104 invasive breast cancers with a broad spectrum of immunohistochemistry scores.
  
  
  METHODS
  This case series involved consecutive patients diagnosed with invasive breast carcinoma with equivocal immunohistochemistry score and referred for further HER2 assessment from the departments of Surgery and/or Clinical Oncology of the two hospitals between January 2013 and February 2014. An additional 10 cases with negative HER2 immunohistochemistry and 11 cases with positive HER2 immunohistochemistry were further included.
  
  
  RESULTS
  The results of both fluorescence in-situ hybridisation and dual in-situ hybridisation were available in 99 of 104 cases, respectively. Student’st test showed no statistically significant difference in the mean number of HER2 count, CEP17 copies, or HER2/CEP17 ratio between that obtained by fluorescence in-situ hybridisation and that obtained by dual in-situ hybridisation. Pearson’s correlation of results for the two assays was strong for HER2/CEP17 signal ratio (R=0.963, P<0.001) and mean HER2 copies per nucleus (R=0.897, P<0.001). Overall agreement was 96.0% (95 out of 99 cases, ĸ0.882). Three of the four discordant cases were equivocal for either fluorescence in-situ hybridisation or dual in-situ hybridisation. The results of immunohistochemistry 0/1+ and 3+ cases showed 100% concordance between the two assays. The failure rate was 0.96% for fluorescence in-situ hybridisation and 3.85% for dual in-situ hybridisation. Cases that failed for fluorescence in-situ hybridisation were successful for dual in-situ hybridisation and vice versa.
  
  
  CONCLUSIONS
  Our study showed that dual in-situ hybridisation is a reliable and useful option for HER2 testing in breast cancer.
authors.forename: Scott M C
authors.initials: SM
authors.lastname: Tang
authors.forename: Inda S
authors.initials: IS
authors.lastname: Soong
authors.forename: M Y
authors.initials: MY
authors.lastname: Luk
authors.forename: Dacita T K
authors.initials: DT
authors.lastname: Suen
authors.forename: F
authors.initials: F
authors.lastname: Hioe
authors.forename: Ellen P S
authors.initials: EP
authors.lastname: Man
authors.forename: Obe K L
authors.initials: OK
authors.lastname: Tsun
authors.forename: U S
authors.initials: US
authors.lastname: Khoo
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D005260:Female; D005784:Gene Amplification; D006723:Hong Kong; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D009361:Neoplasm Invasiveness; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human