Increasing Incidence and Mortality of Gastric Cancer in Immigrant Populations from High to Low Regions of Incidence - a Systematic Review and Meta-Analysis

Abstract Background & Aims Gastric cancer is the leading cause of infection-related cancer death and the third-leading cause of cancer death worldwide. The effect of immigration on gastric cancer risk is not well-defined but might be helpful for screening or surveillance endeavors. We performed a systematic review and meta-analysis to define the risk of gastric cancer in immigrants from high-incidence regions to low-incidence regions (Western Europe, Australia, Brazil, Canada, Israel, and the United States). Methods We searched MEDLINE and EMBASE databases, from January 1980 to January 2019, for studies that identified immigrants from high-incidence regions of gastric cancer, provided clear definitions of immigrant and reference populations, and provided sufficient data to calculate gastric cancer incidence and gastric cancer-related mortality. We performed meta-analyses of standardized incidence ratios (SIR) for first-generation immigrants from high- to low-incidence regions, stratified by immigrant generation, sex, and anatomic and histologic subtype, when data were available. Results We identified 38 cohort studies that met our inclusion criteria. Thirteen studies of 21 distinct populations reported significantly increased SIRs for gastric cancer in first-generation foreign-born immigrants (men SIR range, 1.24–4.50 and women SIR range, 1.27–5.05). The pooled SIR for immigrants with all types of gastric cancer was 1.66 (95% CI, 1.52–1.80) for men and 1.83 (95% CI, 1.69–1.98) for women. Nine studies from 2 high-incidence populations (the former Soviet Union and Japan) reported an increased gastric cancer standardized mortality ratio in first-generation immigrants who migrated to regions of low incidence (former Soviet Union immigrants, 1.44–1.91 for men and 1.40–2.56 for women). Conclusions Immigrants from regions with a high incidence of gastric cancer in regions of low incidence maintain a higher risk of gastric cancer and related mortality, based on a comprehensive systematic review and meta-analysis. Assessment of immigrant generation along with other risk factors might help identify high-risk populations for prevention and therapeutic interventions.