title: Consistent absence of HER2 expression, regardless of HER2 amplification status, in neuroendocrine carcinomas of the stomach.
abstract: OBJECTIVE
  To determine HER2 amplification status and HER2 overexpression status in neuroendocrine carcinomas (NECs) of the stomach.
  
  
  RESULTS
  We analysed 51 gastric NECs, including 15 pure NECs and 36 NECs associated with adenocarcinoma and/or dysplasia, for HER2 amplification by dual-colour chromogenic in-situ hybridization, and for HER2 expression by immunohistochemistry. HER2 amplification was observed in three NECs (6%) and in seven (19%) cases of adenocarcinoma/dysplasia associated with NEC. Immunohistochemically, all of the NECs, including those showing HER2 amplification, lacked HER2 expression. On the other hand, positive and equivocal HER2 overexpression was observed in three (8%) and six (17%) cases of adenocarcinoma/dysplasia associated with NEC, respectively.
  
  
  CONCLUSIONS
  HER2 expression is consistently absent in gastric NECs, regardless of HER2 amplification status or association with HER2-positive adenocarcinoma/dysplasia components. Accordingly, HER2 is unlikely to be a valid therapeutic target in gastric NECs. Also, the absence of HER2 expression in NECs could be one of the causes of intratumoral heterogeneity of HER2 expression in gastric cancers.
authors: Pathology Division, National Cancer Center Hospital, Tokyo, Japan; Gastric Surgery Division, National Cancer Center Hospital, Tokyo, Japan.
authors: Michihiro
authors: M
authors: Ishida
authors: Shigeki
authors: S
authors: Sekine
authors: Hirokazu
authors: H
authors: Taniguchi
authors: Takeo
authors: T
authors: Fukagawa
authors: Hitoshi
authors: H
authors: Katai
authors: Ryoji
authors: R
authors: Kushima
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D018278:Carcinoma, Neuroendocrine / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005784:Gene Amplification; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human
keywords: HER2; neuroendocrine carcinoma; stomach