Helicobacter pylori-CagA seropositivity and nitrite and ascorbic acid food intake as predictors for gastric cancer.

A hospital-based case-control study was carried out between 1994 and 1996 to evaluate the risk of gastric cancer (GC) according to Helicobacter pylori-CagA (+) seropositivity, nitrite and ascorbic acid intake. Three geographical areas of Mexico were selected on the basis of their contrasting dietary patterns and H. pylori seroprevalence. Nitrite and ascorbic acid consumption were estimated by interview among 211 cases and 454 matched controls. Serum antibodies against IgG H. pylori and CagA were detected by immunosorbent assays. The adjusted risk for GC was significantly higher among CagA+ subjects compared with those that were CagA negative (Odds Ratio (OR)=2.04 95% Confidence Interval (CI) 1.37-3.02 P for trend P < 0.001), this effect remained significant among diffuse GC cases (OR 2.05 95% CI 1.25-3-36). No significant effects due to nitrite and ascorbic consumption or interactions of these nutrients with CagA seropositivity were detected. Seropositivity to H. pylori CagA+ strains may be an independent factor for diffuse GC in Mexico.