Serum Antibody Against H elicobacter 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 .