title: Serum antibody against Helicobacter pylori FlaA and risk of gastric cancer.
abstract: BACKGROUND
  Helicobacter pylori (H. pylori) infection is a major risk factor for gastric cancer (GC); however, only a minority of infected individuals develops GC. We aim to assess the association between serostatus of antibody against H. pylori flagellin A (FlaA) and risk of GC and to evaluate the value of serum FlaA antibody as a novel screening biomarker for GC risk.
  
  
  METHODS
  A hospital-based case-control study including 232 cases and 264 controls was conducted. Logistic regression was adopted to analyze the association between the serostatus of FlaA antibody and risk of GC. Serum FlaA antibody was measured by an enzyme-linked immunosorbent assay (ELISA). Receiver operating characteristic (ROC) curve was used to evaluate the screening efficacy and to identify a cutoff point of serum FlaA antibody level.
  
  
  RESULTS
  Helicobacter pylori infection was associated with an increased risk of GC (p = .007). A positive association between serum FlaA antibody and GC risk was observed in overall subjects and H. pylori-positive subjects (OR [95% CI]: 6.8 [4.3-10.7] and 6.9 [3.6-13.4], respectively; p < .001). The seropositivity of FlaA antibody was strongly related to GC risk in a dose-dependent manner (p for trend < .001). The optimal cutoff value (OD) was 0.1403, providing a sensitivity of 74.1% and a specificity of 64.4%. The area under the ROC curve (AUC) was 0.74 in overall subjects and 0.73 in H. pylori-positive subjects, respectively.
  
  
  CONCLUSIONS
  FlaA was an independent risk factor for H. pylori-related GC. Serum FlaA antibody may serve as a novel noninvasive biomarker for early detection of GC.
authors.affiliation: Department of Epidemiology, College of Public Health, Harbin Medical University, Harbin, Heilongjiang Province, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Tian
authors.forename: Yunhe
authors.initials: Y
authors.lastname: Jia
authors.forename: Kexin
authors.initials: K
authors.lastname: Yuan
authors.forename: Lina
authors.initials: L
authors.lastname: Huang
authors.forename: Christina
authors.initials: C
authors.lastname: Nadolny
authors.forename: Xiaoqun
authors.initials: X
authors.lastname: Dong
authors.forename: Xiyun
authors.initials: X
authors.lastname: Ren
authors.forename: Jingjing
authors.initials: J
authors.lastname: Liu
mesh_terms: D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005408:Flagellin / Q000276:immunology*; D016481:Helicobacter Infections / Q000150:complications*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000175:diagnosis*
chemical_list: D000907:Antibodies, Bacterial; D014408:Biomarkers, Tumor; D005408:Flagellin; C067138:flaA protein, bacteria
keywords: H. pylori FlaA protein; case-control study; gastric cancer; serum antibody