Epstein-Barr virus EBV-positive gastric cancer ? A distinct etiology entity?

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Springer

MedWire News>: Gastric cancers containing the Epstein-Barr virus (EBV) should be considered a distinct etiologic entity, a team of experts believes.

Their conclusion is based on a pooled analysis of data on more than 5000 cases of gastric cancer, which identified a number of distinct clinical and genetic features specific to EBV-positive tumors.
"Our findings reveal a complex interplay of factors influencing EBV's presence in gastric tumors and may provide important clues to understanding its etiologic significance," write Constanza Camargo (National Institutes of Health, Rockville, Maryland, USA) in the British Journal of Cancer.

In their study, Camargo's team expanded on a previous meta-analysis of the prevalence of EBV in gastric cancer. Using the same 12 population-based studies, they extracted individual-level patient data to identify variables associated with EBV-positive cancer.

The final analysis included data on 5081 gastric cancer patients, representing 12 distinct populations living in Asia or Latin America. In each of the studies, EBV status was determined using a common protocol - namely, EBV-encoded small RNA in situ hybridization.

The overall prevalence of EBV positivity was 7.7%, but this value varied widely among populations, from 1.9% (Pakistan) to 16.8% (Chile).

After accounting for in-population clustering, and adjusting for multiple covariates, EBV positivity was significantly associated with four features: male gender, non-antral subsite, diffuse-type histology, and studies conducted in the Americas.

Further analysis revealed that male gender interacted with both age and anatomic subsite, such that male predominance decreased with increasing age for both antral and non-antral subsites.
In a final model that included these two interactions, the authors confirmed the positive associations of EBV positivity with diffuse-type histology (odds ratio [OR]=2.0) and individuals from the Americas (OR=2.3).
Camargo and co-workers admit that the specific role of EBV in gastric carcinogenesis has not yet been elucidated, but say their analysis supports its etiologic significance.

"Histologic specificity and geographic variation suggest that EBV-positive gastric cancer is a distinct entity," they conclude. "The pairwise interactions that we found among age, sex, and anatomic subsite are novel and should be explored further."

MedWire (http://www.medwire-news.md/ ) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Joanna Lyford