Prevalence and Incidence of Gastric Cancer Among Helicobacter pylori-Naïve Individuals in Japan: A Systematic Review and Meta-Analysis.

[BACKGROUND AND AIM] With Helicobacter pylori (H. pylori)-naïve adults becoming increasingly common in Japan, the magnitude of their gastric cancer (GC) risk remains uncertain and warrants clarification.

[MATERIALS AND METHODS] We conducted a systematic review and meta-analysis to estimate the screen-detected prevalence and incidence of GC among H. pylori-naïve individuals in Japan. MEDLINE and EMBASE were searched for studies published between January 2014 and August 2024. Eligible studies included cross-sectional or cohort designs that confirmed H. pylori-naïve status using ≥1 validated test and reported histologically diagnosed GC. Generalized linear mixed-effects models were used to derive pooled estimates.

[RESULTS] Of 652 screened articles, six were included (n = 248 482; four cohorts, two cross-sectional). Among these, 96 GC cases were identified. The mean age ranged from 48 to 58 years, with a male proportion between 35% and 60%. The pooled screen-detected prevalence of GC was 0.029% (95% confidence interval [CI], 0.006-0.137), equivalent to approximately one case per 3500 individuals screened. The pooled incidence from four cohorts (218 000 person-years) was 1.40 per 10 000 person-years (95% CI, 0.61-3.23), based on 30 incident cases. Pooled screen-detected prevalence of invasive GC was 0.015% (95% CI, 0.002-0.094), 80.6% of which were histologically diagnosed as gastric adenocarcinoma of the fundic gland type, an indolent subtype.

[CONCLUSIONS] The screen-detected prevalence and incidence of GC among H. pylori-naïve individuals were low. The present meta-analysis provides important baseline data to characterize GC risk among H. pylori-naïve individuals in Japan.