About 9% of gastric carcinomas have Epstein–Barr virus (EBV) in the tumor cells, but it is unclear whether viral presence influences clinical progression.
Dr Constanza Camargo and colleagues from Maryland, USA therefore examined a large multicenter case series for the association of tumor EBV status with survival after gastric cancer diagnosis, accounting for surgical stage and other prognostic factors.
The research team combined individual-level data on 4599 gastric cancer patients diagnosed between 1976 and 2010 from 13 studies in Asia, Europe, and Latin America.
EBV positivity of tumors was assessed by in situ hybridization.
|Tumor EBV positivity was 8% overall|
Mortality hazard ratios for EBV positivity were estimated by Cox regression models stratified by study, adjusted for distributions of sex, age, stage, tumor histology, anatomic subsite and year of diagnosis.
Variations by study and continent were assessed using study-specific hazard ratios for EBV positivity.
The team observed that during median 3 years follow-up, 49% of patients died.
Stage was strongly predictive of mortality, with unadjusted hazard ratios of 3 for stage II, 8 for stage III, and 13 for stage IV.
The research team found that tumor EBV positivity was 8% overall, and inversely associated with stage.
Adjusted for stage and other confounders, EBV positivity was associated with lower mortality, with low heterogeneity among the study populations.
The team noted that the association did not significantly vary across patient or tumor characteristics.
The researchers found no significant variation among the 3 continent-specific hazard ratios.
Dr Camargo's team concludes, "Our findings suggest that tumor EBV positivity is an additional prognostic indicator in gastric cancer."
"Further studies are warranted to identify the mechanisms underlying this protective association."