Helicobacter pylori infection and markers of gastric cancer risk in Alaska Native persons: a retrospective case-control study.

Abstract

Alaska Native persons experience gastric cancer incidence and mortality rates that are three to four times higher than in the general United States population. To evaluate pepsinogen I, pepsinogen I/II ratio, anti-Helicobacter pylori and cytotoxin-associated gene A (CagA) antibody levels, and blood group for their associations with gastric cancer development in Alaska Native people. The present analysis was a retrospective case-control study that matched gastric cancers reported to the Alaska Native Tumor Registry from 1969 to 2008 to three controls on known demographic risk factors for H pylori infection, using sera from the Alaska Area Specimen Bank. Conditional logistic regression evaluated associations between serum markers and gastric cancer. A total of 122 gastric cancer cases were included, with sera predating cancer diagnosis (mean = 13 years) and 346 matched controls. One hundred twelve cases (91.8%) and 285 controls (82.4%) had evidence of previous or ongoing H pylori infection as measured by anti-H pylori antibody levels. Gastric cancer cases had a 2.63-fold increased odds of having positive anti-H pylori antibodies compared with their matched controls (P=0.01). In a multivariate model, noncardia gastric cancer (n=94) was associated with anti-H pylori antibodies (adjusted OR 3.92; P=0.004) and low pepsinogen I level (adjusted OR 6.04; P=0.04). No association between gastric cancer and blood group, anti-CagA antibodies or pepsinogen I/II ratio was found. Alaska Native people with gastric cancer had increased odds of previous H pylori infection. Low pepsinogen I level may function as a precancer marker for noncardia cancer.