Serum antibody against Helicobacter pylori FlaA and risk of gastric cancer.

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.