title: HER2 expression in gastric cancer: Rare, heterogeneous and of no prognostic value - conclusions from 924 cases of two independent series.
abstract: BACKGROUND
  Patients with gastric cancer (GC) have a poor survival and biologicals such as Trastuzumab have not been used routinely in these patients. Existing data on HER2 expression and its clinical relevance in GC are still limited and controversial.
  
  
  METHODS
  HER2 expression was investigated by immunohistochemistry in 418 GC from Germany and 506 GC from England. Results were compared to clinicopathological parameters and patient survival.
  
  
  RESULTS
  Less than 10% of all GC showed HER2 expression in more than 5% of tumour cells and 91% of these were intestinal type GC. In both series, no relationship was found between HER2 expression, patient survival or TNM stage. Marked intratumoural heterogeneity was noted.
  
  
  CONCLUSIONS
  This is the largest study to date demonstrating in two independent series that HER2 expression is not related to gastric cancer patient prognosis and that only a very small subgroup of intestinal type GC may potentially respond to HER2 targeting therapy. Due to prominent intratumoural heterogeneity of HER2 expression in GC, HER2 testing in endoscopic biopsies before treatment will be prone to false negative results.
authors.affiliation: Pathology & Tumour Biology, Leeds Institute of Molecular Medicine, University of Leeds, Leeds, UK. h.i.grabsch@leeds.ac.uk
authors.forename: Heike
authors.initials: H
authors.lastname: Grabsch
authors.forename: Shivan
authors.initials: S
authors.lastname: Sivakumar
authors.forename: Sally
authors.initials: S
authors.lastname: Gray
authors.forename: Helmut E
authors.initials: HE
authors.lastname: Gabbert
authors.forename: Wolfram
authors.initials: W
authors.lastname: Müller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004739:England; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality* / Q000473:pathology; D013534:Survival; D055815:Young Adult
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human