title: Clinical significance of IgG antibody titer against Helicobacter pylori.
abstract: BACKGROUND
  We clarified the clinical significance of measurement of IgG antibody titers against Helicobacter pylori using data from a nested case-control study from a large-scale cohort study in Japan.
  
  
  METHODS
  Participants included 36,745 subjects from the Japan Health Center-based Prospective Study who responded to the baseline questionnaire and provided a blood sample. Subjects were aged 40-69 years and were followed over 15 years after initial sampling. Controls were matched to 511 gastric cancer patients. Plasma surface antigen (Hp)-IgG titer was measured using ELISA, and mucosal atrophy was determined by measuring pepsinogen I and II levels.
  
  
  RESULTS
  Seropositive subjects with low Hp-IgG titer and mucosal atrophy showed a higher risk for gastric cancer than high-titer subjects. Odds ratio (OR) referred to cases with true negative IgG titers and no mucosal atrophy. In moderately atrophic subjects, the low titer OR was 19.0, with a 95% confidence interval (CI) of 7.7-46.9, and 12.5 for high titer, with a 95% CI of 5.2-30.0. In severely atrophic subjects, the low titer OR was almost double that of high-titer subjects (OR = 30.2, 95% CI = 12.4-73.7 and OR = 15.9, 95% CI = 6.3-40.3, respectively). These associations were observed more frequently for differentiated than undifferentiated gastric cancer.
  
  
  CONCLUSIONS
  Combination assay with Hp-IgG titer and pepsinogens may help identify groups at high risk for gastric cancer. Subjects with low Hp-IgG titer and mucosal atrophy were at extremely high risk for gastric cancer, particularly differentiated cancer. Subjects with this background may require ongoing observation and periodic endoscopic examination for early cancer detection.
authors.affiliation: Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Chuo-ku, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Tatemichi
authors.forename: Shizuka
authors.initials: S
authors.lastname: Sasazuki
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology*; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005753:Gastric Mucosa / Q000737:chemistry / Q000473:pathology; D016481:Helicobacter Infections / Q000150:complications / Q000276:immunology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology*; D007564:Japan; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020116:Pepsinogen A / Q000032:analysis; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D020116:Pepsinogen A