In a small but significant percentage (9%) of gastric cancers, tumor cells contain Epstein-Barr virus (EBV). To assess whether EBV positivity is associated with cancer outcomes, investigators pooled data on 4599 patients with invasive gastric cancer from 13 case series./p>
Median follow-up was 3.0 years. The prevalence of EBV-positive cancer was 8.2%. In multivariate analysis, EBV positivity was associated with lower tumor stage (odds ratio, 0.79 per unit change in stage; 95% confidence interval, 0.69–0.91). In unadjusted regression analysis, higher tumor stage was associated with higher mortality, with hazard ratios of 3.1 for stage II, 8.1 for stage III, and 13.2 for stage IV in comparison with stage I. Median survival was higher in patients with EBV-positive tumors than in patients with EBV-negative tumors (8.5 years vs. 5.3 years; P=0.0006). After adjusting for stage and other potential confounders, EBV positivity was associated with lower mortality (HR, 0.72; 95% CI, 0.61–0.86). Heterogeneity among studies was low.