Helicobacter pylori seropositivity and subsite-specific gastric cancer risks in Linxian, China

Background: Helicobacter pylori carriage (i.e., persistent exposure to the organism without gastric epithelial cell invasion) is an established risk f actor for noncardia gastric cancer, However, its association with the risk of cancer of the gastric cardia is controversial. Consequently, we designed this prospective, nested case-control study to further explore the subsite -specific gastric cancer risks associated with H. pylori seropositivity (a surrogate marker for persistent exposure), Methods: A total of 99 patients with gastric cardia cancer, 82 patients with noncardia gastric cancer, and 192 cancer-free subjects were selected from among the participants (n = 29 584) of a nutrition intervention trial previously conducted in Linxian, Chi na. H, pylori seropositivity was determined by assaying for the presence of H. pylori whole cell and CagA antibodies in baseline serum samples from al l subjects. Seropositivity was defined as one or both serum assays being po sitive. Odds ratios (ORs) for subsite-specific gastric cancer were estimate d by multivariate logistic regression analyses. All statistical comparisons were two-sided (alpha =.05), Results: H, pylori seropositivity rates for s ubjects with gastric cardia cancer, noncardia gastric cancer, and gastric c ardia and noncardia cancers combined were 70% (P = .02), 72% (P = .01), and 71% (P = .003) compared with 56% for cancer-free control subjects. OR esti mates for H. pylori seropositivity were 1.87 (95% confidence interval [CI] = 1.10 to 3.17) for gastric cardia cancer, 2.29 (95% CI = 1.26 to 4.14) for noncardia gastric cancer, and 2.04 (95% CI = 1.31 to 3.18) for gastric car dia and noncardia cancers combined. Conclusions: H. pylori seropositivity w as associated with increased risks for both gastric cardia cancer and nonca rdia gastric cancer in this well-characterized cohort. Thus, H. pylori carr iage may increase the risk of cancer throughout the stomach.