Serological response to Helicobacter pylori infection among Latin American populations with contrasting risks of gastric cancer

Gastric cancer is a rare outcome of chronic Helicobacter pylori infection. Serologic profiles may reveal bacterial, environmental and/or host factors associated with cancer risk. We therefore compared specific anti-H. pylori antibodies among populations with at least twofold differences in gastric cancer mortality from Mexico, Colombia and Chile. Our study included 1,776 adults (mean age 42 years) from three nationally representative surveys, equally divided between residents of high- and low-risk areas. Antibodies to 15 immunogenic H. pylori antigens were measured by fluorescent bead-based multiplex assays; results were summarized to identify overall H. pylori seropositivity. We used logistic regression to model associations between antibody seroreactivity and regional cancer risk (high vs. low), adjusting for country, age and sex. Both risk areas had similar H. pylori seroprevalence. Residents in high- and low-risk areas were seroreactive to a similar number of antigens (means 8.2 vs. 7.9, respectively; adjusted odds ratio, OR: 1.02, p=0.05). Seroreactivities to Catalase and the known virulence proteins CagA and VacA were each significantly (p<0.05) associated with residence in high-risk areas, but ORs were moderate (1.26, 1.42 and 1.41, respectively) and their discriminatory power was low (area under the curve<0.6). The association of Catalase was independent from effects of either CagA or VacA. Sensitivity analyses for antibody associations restricted to H. pylori-seropositive individuals generally replicated significant associations. Our findings suggest that humoral responses to H. pylori are insufficient to distinguish high and low gastric cancer risk in Latin America. Factors determining population variation of gastric cancer burden remain to be identified. What's new? Can antibody patterns reveal a population's gastric cancer risk? These authors tested H. pylori antibodies from individuals in regions of high and low risk in three countries in Latin America. In the largest serological study to date, they measured 15 different anti-H. pylori antibodies to find out whether people in high-risk populations had a different set of antibodies than those in low-risk areas. Persons from high-risk areas had more antibodies to certain proteins, including CagA, suggesting that their infecting strains may be more virulent. However, the difference in immune response was not pronounced enough to reliably assess gastric cancer risk.