title: Droplet digital PCR measurement of HER2 in patients with gastric cancer.
abstract: BACKGROUND
  Although there are some new criteria for human epidermal growth factor receptor 2 (HER2) expression with immunohistochemistry/fluorescence in situ hybridisation (IHC/FISH) in gastric cancer, the method is still ambiguous and is somewhat dependent on the subjective qualities of the evaluator.
  
  
  METHODS
  We used droplet digital polymerase chain reaction (ddPCR) to evaluate HER2 amplification in formalin-fixed and paraffin-embedded (FFPE) samples and cell-free serum circulating tumour DNA (ctDNA) in 25 patients with gastric cancer.
  
  
  RESULTS
  The concordance rate of HER2 amplification examined in FFPE samples with ddPCR and IHC/FISH was 92% (23 out of 25). The concordance rate of FFPE with ctDNA was not high (62.5%); however, patients who were HER2-positive by ctDNA had significantly shorter survival compared with HER2-negative patients.
  
  
  CONCLUSIONS
  Our results demonstrated that this ddPCR method was as effective as IHC/FISH and therefore might become a standard method for analysing not only FFPE but also ctDNA.
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kinugasa
authors.affiliation: 1] Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan [2] Department of Molecular Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nouso
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Miyahara
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Morimoto
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Dohi
authors.affiliation: BioRepository/BioMarker Analysis Center, Innovative Clinical Medicine, Okayama University Hospital, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Matsubara
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Okada
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8558, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004247:DNA / Q000097:blood; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008297:Male; D008875:Middle Aged; D016612:Paraffin Embedding / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D013274:Stomach Neoplasms / Q000097:blood / Q000201:enzymology* / Q000235:genetics*
chemical_list: D004247:DNA; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human