title: Overexpression of HER2/neu in solid tumours: an immunohistochemical survey.
abstract: OBJECTIVE
  Using a standardized immunohistochemical assay we have evaluated 575 primary neoplasms of different histogenesis to determine the incidence of HER2 overexpression in some of the most common categories of human solid neoplasms. This study addresses the variable incidence of HER2 overexpression previously published for some tumour types.
  
  
  RESULTS
  The immunohistochemical staining was performed on paraffin sections of surgical specimens and a well-defined scoring system based upon numbers of HER2 receptors expressed on the cell surface was applied. Overexpression of HER2 as defined as a HER2 score of equal or greater than 2 was seen in breast cancer (22%), pulmonary adenocarcinoma (28%), colorectal adenocarcinomas (17%), pulmonary squamous (11%) and gastric adenocarcinomas (11%). As expected, the proportion of cases with a HER2 score of 3 was highest in breast cancer. Contrary to published results prostate and pancreas adenocarcinomas showed a very low incidence of HER2 overexpression.
  
  
  CONCLUSIONS
  Overexpression of HER2 is detected immunohistochemically in a proportion of epithelial neoplasms of diverse histogenesis in addition to ductal breast cancer. The standardized format of the assay will allow comparative analyses of studies performed at different institutions.
authors.affiliation: Department of Pathology, Genentech Inc., South San Francisco, CA 94080, USA. hkoeppen@gene.com
authors.forename: H K
authors.initials: HK
authors.lastname: Koeppen
authors.forename: B D
authors.initials: BD
authors.lastname: Wright
authors.forename: A D
authors.initials: AD
authors.lastname: Burt
authors.forename: P
authors.initials: P
authors.lastname: Quirke
authors.forename: A M
authors.initials: AM
authors.lastname: McNicol
authors.forename: N O
authors.initials: NO
authors.lastname: Dybdal
authors.forename: M X
authors.initials: MX
authors.lastname: Sliwkowski
authors.forename: K J
authors.initials: KJ
authors.lastname: Hillan
mesh_terms: D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods*; D008297:Male; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D011933:Reagent Kits, Diagnostic; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*
chemical_list: D011933:Reagent Kits, Diagnostic; D018719:Erb-b2 Receptor Tyrosine Kinases