Helicobacter pylori Infection, Intestinal Metaplasia, and Gastric Cancer Risk in Eastern Siberia

Background: The incidence of gastric cancer (GC) is extremely high in Russia and eastern Siberia, where information on the epidemiology of Helicobacter pylori infection is fragmentary. Aims: To assess the prevalence of both H. pylori infection (including CagA status) and intestinal metaplasia (IM) in Russian and eastern Siberian populations carrying a different risk of GC. Materials and Methods: A sample of 2129 consecutive patients was considered, including 689 Europoids and 1440 Mongoloids (493 Evenks, 533 Khakass people, and 414 Tuvans), who all underwent serum sampling and upper gastrointestinal endoscopy. H. pylori status was established (ELISA, urease test, and histology), and IgG anti-CagA antibodies were assessed (ELISA) in H. pylori-positive cases. At least 3 biopsy samples per patient were considered, and IM was scored as present versus absent. The prevalence of H. pylori, CagA+ve status, and IM was compared with the incidence of GC according to the regional cancer registries. Results: The prevalence of H. pylori was similar for the Europoids and Mongoloids (93.6 vs 94.3%). The prevalence of CagA+ve infection was as follows: Europoids 61.2%, Evenks 36.4%, Khakass 44.0%, Tuvans 60.0% (p(1vs2) < .001; p(1vs3) < .001; p(2vs4) < .001; p(3vs4) < .001). The prevalence of IM was as follows: Europoids 10.7%, Evenks 5.1%, Khakass 9.8%, and Tuvans 23.4% (p(1vs2) = .001; p(1vs4) < .001; p(2vs4) < .001; p(3vs4) < .001). The incidence of GC (per 100,000 population/year) was as follows: Europoids 33.2; Evenks 18.2; Khakass 20.2; Tuvans 50.7 (p(1vs2) = 0.04; p(1vs3) = .05; p(2vs4) < .001; p(3vs4) < .001). Conclusion: H. pylori infection is consistently high in Russian and eastern Siberian populations; ethnicities with similar prevalence of CagA+ve status had different prevalence of IM and incidence of GC. As expected, IM prevalence correlated with the incidence of GC. Host-related and/or environmental factors may explain discrepancies between H. pylori status, the prevalence of IM, and the incidence of GC.