Global Epidemiology of PD-L1 Expression in Epstein-Barr Virus-Associated Gastric Cancer: A Systematic Review and Meta-Analysis.

Background: Epstein-Barr virus-associated gastric cancer (EBVaGC) accounts for ~ 10% of gastric cancers (GC). Programmed death-ligand 1 (PD-L1) expression plays a key role in immune evasion and response to immunotherapy, but its correlation with EBVaGC remains unclear.

Methods: We searched PubMed, Embase, and Cochrane databases for studies evaluating PD-L1 expression in EBVaGC. The primary outcome was the association between EBV and PD-L1 expression. Statistical analyses were performed using RStudio.

Results: A total of 53 studies with 17,806 patients were included. PD-L1 expression in EBVaGC was 10.34% (95% CI: 6.30-14.38; I = 94.8%; p < 0.01). Prevalence varied by income level: high-income (8.28%), upper-middle-income (15.18%), and lower-middle-income countries (1.03%). By continent, PD-L1 expression rates were highest in Asia (12.44%) and lowest in Africa (1.03%). Among countries, China (21.51%) and the Czech Republic (22.50%) had the highest prevalence, while the Netherlands (0.83%) and Morocco (1.03%) had the lowest.

Conclusion: Our findings reinforce the relevance of molecular classification, particularly the assessment of Epstein-Barr virus status, as a promising tool for improving patient stratification and guiding therapeutic decisions in gastric cancer. These results may contribute to advancing future research aimed at validating and expanding the use of these biomarkers globally.