title: Bright-field HER2 dual in situ hybridization (DISH) assay vs fluorescence in situ hybridization (FISH): focused study of immunohistochemical 2+ cases.
abstract: OBJECTIVE
  To compare the INFORM HER2 bright-field dual in situ hybridization (DISH) DNA probe cocktail assay with the PathVysion fluorescence in situ hybridization (FISH) assay on 103 invasive breast carcinomas with a 2+ score on immunohistochemistry (IHC).
  
  
  METHODS
  The cases were categorized as positive, equivocal, or negative for HER2 gene amplification using the 2007 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2:CEP17 ratio criteria and also based on mean HER2 gene copies/cell. The third criterion used a HER2:CEP17 ratio of 2 to categorize cases as positive or negative.
  
  
  RESULTS
  The agreement between FISH and DISH was 85% using the 2007 ASCO/CAP ratio criterion, 79% using the mean HER2 gene copies/cell criterion, and 92% using the 2.0 cutoff HER2:CEP17 ratio criterion. In addition, 20 known IHC 3+ breast carcinomas analyzed by DISH showed clusters of the HER2 gene consistent with unequivocal amplification.
  
  
  CONCLUSIONS
  Despite some technical and interpretational issues associated with DISH, it compares favorably with FISH in this group of challenging breast cancer cases.
authors.affiliation: Magee-Womens Hospital of University of Pittsburgh Medical Center, 300 Halket St, Pittsburgh, PA 15213; rbhargava@mail.magee.edu.
authors.forename: Faye F
authors.initials: FF
authors.lastname: Gao
authors.forename: David J
authors.initials: DJ
authors.lastname: Dabbs
authors.forename: Kristine L
authors.initials: KL
authors.lastname: Cooper
authors.forename: Rohit
authors.initials: R
authors.lastname: Bhargava
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D002886:Chromosomes, Human, Pair 17 / Q000648:ultrastructure; D005260:Female; D018734:Genes, erbB-2; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis*
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases
keywords: DISH; FISH; HER2 gene; HER2 immunohistochemistry; IHC score 2+