title: Serum HER2 extracellular domain as a potential alternative for tissue HER2 status in metastatic gastric cancer patients.
abstract: OBJECTIVE
  We investigated whether serum concentrations of the HER2 extracellular domain (ECD) can be used as an alternative to test tissue HER2 status in metastatic gastric cancer.
  
  
  METHODS
  A total of 133 cases of metastatic gastric cancer were included in present study. Serum HER2 ECD was measured by chemiluminescence immunoassay (CLIA). Receiver operating characteristic curve analysis was used to determine optimal serum HER2 ECD concentrations for differentiation between positive and negative HER2 status.
  
  
  RESULTS
  The median level of serum HER2 ECD was 9.6 ng/ml in metastatic gastric cancer patients. There was a significant relationship between serum and tissue levels of HER2 protein (p < 0.001). Area under the curve for serum HER2 ECD was 0.771 (95% CI: 0.682-0.860).
  
  
  CONCLUSIONS
  Levels of serum HER2 ECD are highly correlated with tissue HER2 status in metastatic gastric cancer. Serum HER2 ECD assay can be considered as a potential alternative for tissue HER2 status.
authors.affiliation: Department of Gastrointestinal Oncology, Key Laboratory of Carcinogenesis & Translational Research (Ministry of Education), Peking University Cancer Hospital & Institute, Beijing, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Peng
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaotian
authors.initials: X
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhou
authors.forename: Ming
authors.initials: M
authors.lastname: Lu
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Shen
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood* / Q000737:chemistry* / Q000378:metabolism; D005110:Extracellular Space / Q000201:enzymology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D017434:Protein Structure, Tertiary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000097:blood* / Q000737:chemistry* / Q000378:metabolism; D012189:Retrospective Studies; D012995:Solubility; D013274:Stomach Neoplasms / Q000097:blood* / Q000378:metabolism / Q000473:pathology*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases
keywords: ECD; HER2; extracellular domain; metastatic gastric cancer; serum