Epstein-Barr virus-associated gastric adenocarcinomas among Koreans

Epstein-Barr virus (EBV)-associated gastric carcinomas have been reported from various regions of the world. Epstein-Barr virus appears to be pathogenetically related to some gastric carcinomas. To determine the incidence of EBV association with gastric carcinomas among Koreans, the authors have studied EBV genome expression in 89 consecutive patients with gastric carcinomas diagnosed at the Catholic University Hospitals in Seoul, Korea, using in situ hybridization (ISH) for EBV-encoded small RNAs (EBERs), and immunohistochemistry for EBV latent membrane proteins (LMP) and CD21 antigen on paraffin sections. Thirty-seven gastric specimens with benign ulcer disease were used controls. EBV-encoded small RNAs were expressed in tumor cell nuclei in 12 patients (13.5%). None of the controls or benign portions of the cases were positive. In the positive cases, all tumor cell nuclei were uniformly stained and the staining intensity was strong. Immunohistochemistry for LMP was positive in 3 of 12 EBERs positive patients and none of EBERs negative patients. EBV latent membrane proteins was localized only in the lymphoid cells infiltrating the tumor in two patients, and tumor cells as well as infiltrating lymphoid cells in one patient. These results indicate that the rate of EBV association with gastric carcinomas in Koreans is relatively high and comparable to other Far Eastern Asian regions. The expression pattern in EBV-associated gastric carcinomas is similar to those of nasopharyngeal carcinomas in which clonality analysis using specific probes to the tandem repeat region of EBV yielded single episomal bands suggesting that EBV infection in EBV-associated gastric carcinomas are also clonal and pathogenetically related to the neoplasm. However, the mechanism of tumorigenesis remains to be elucidated.