Epstein-Barr virus-associated gastric carcinoma in Lima, Peru.

Abstract

We examined 254 gastric carcinomas (GCs) diagnosed in four hospitals in Lima, Peru, and its suburban area during the period between 1994-2001. Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) was identified by the in situ hybridization (ISH) technique to detect EBV-encoded small RNA (EBER) in gastric tissue. EBVaGCs, where EBER ISH staining was observed in all carcinoma cells, accounted for 3.9% (10/254) of gastric adenocarcinomas, the lowest frequency ever reported in Latin American countries. EBVaGC incidence rates in Peru, which we estimated on the basis of the present study and cancer incidence in Lima, were 0.8 per 100,000 among men and 0.5 per 100,000 among women. These estimates are much lower than those reported in our previous studies in Colombia (4.1 and 1.4 per 100,000 among men and women, respectively), a neighboring country, and in Japan (6.4 and 1.1 per 100,000 among men among women, respectively). Interestingly, EBVaGC in Peru showed no evident male predominance, as opposed to the findings reported in a majority of studies. Other clinicopathological features of EBVaGC in Peru were similar to those found in literature: EBVaGC showed no age dependence, a predominance in the non-antrum part of the stomach, and high frequencies in histological subtypes of moderately differentiated tubular adenocarcinoma and solid poorly differentiated adenocarcinoma. There was a case of well-differentiated adenocarcinoma showing a partial EBER-1-positive staining. In this carcinoma, the tumor in the body (middle third of the stomach) was EBER-1 positive but the tumor in the stomach antrum showed no noticeable EBER-1 ISH staining. We suspect this was a case of synchronous double carcinomas. Further studies are needed to identify the cause of the low frequency and lack of male predominance of EBVaGC in Peru.