Characterization of EBV-associated gastric cancers

Abstract

Worldwide, Gastric Cancer (GC) is the sixth most common malignancy with nearly 1 million new cases estimated in 2012. In Portugal, data reveal that GC is the fifth most frequent cancer with about 3000 new cases per year. Moreover GC has still a higher mortality rates being responsible for 1387 deaths in men and 898 in women. Recent data showed that Epstein-Barr virus (EBV) has been detected in different histopathological subtypes of gastric carcinoma and EBV-associated gastric carcinoma (EBVaGC) accounts about 10% of all cases. This study pretends to characterize EBVaGC in our population through detection of EBV in gastric carcinoma tissues from 136 consecutive patients attended at Portuguese Institute of Oncology of Porto (IPO Porto FG EPE) in the year of 2011. EBV detection was performed by in situ hybridization (ISH) targeting EBV-encoded small RNA (EBER-ISH) with an EBER-DNA probe. The results showed that in our population EBVaGC represent 6.6% of all GC cases. Analyzing the distribution of EBV among the different histological types, we observed that EBV was present in 6.6% of intestinal-types, 11.1% of indeterminate types, 100% of lymphoepithelioma-like carcinomas and there were no positive cases among diffuse types (p<0.001). The risk analysis revealed that, despite there are not statistically significant differences, patients with intestinal (p=0.350; OR= 1.98, 95% CI=0.37-10.5) and indeterminate (p=0.238; OR=2.78, 95% CI=0.55-15.5) GC have an increased risk of having an EBVaGC; while diffuse GC (p=0.078; OR=0.14, 95% CI=0.01-2.58) have a decreased risk of having an EBVaGC. Regarding tumor location, the results demonstrated that patients with tumors in upper regions of stomach have an increased risk to have an EBVaGC (p=0.032; OR=4.68, 95% CI=1.11-19.7). In conclusion, the EBV infection rate among gastric carcinomas in Portugal is similar to that ascertained in other countries. Conversely, the clinicopathological features showed differences when compared with previous studies, mainly the absence of EBV in diffuse-type gastric carcinomas. This is the first study to characterize EBVaGC in Portugal which reinforce the need of further studies to clarify the role of EBV and to explore its potential value as predictive/prognostic biomarker in gastric cancer development.

Date of Award	18 Mar 2015
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Hugo Manuel Lopes Sousa (Supervisor) & Joana Ribeiro (Co-Supervisor)