Relationship between Epstein-Barr virus-encoded RNA expression, apoptosis and lymphocytic infiltration in gastric carcinoma with lymphoid-rich stroma

Objective: To investigate the association of apoptosis with apoptotic proteins and Epstein-Barr virus (EBV) expression in gastric carcinoma with lymphoid-rich stroma (GCLRS) in order to clarify the relationship between lymphocytic infi ltration, EBV expression and apoptosis in gastric carcinoma. Subjects and Methods: We performed immunohistochemical stains for bcl-2, bax and in situ hybridization for EBV-encoded RNA and the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling technique using the 24 cases of GCLRS and 23 cases of gastric carcinoma with lymphoid-poor stroma (GCLPS) out of 1,635 cases of gastric carcinoma. Results: The prevalence of GCLRS was 1.47% (24/1,635). The prevalence of EBV involvement in GCLRS (79%, 19/24) was significantly higher than in GCLPS (8.7%, 2/23). Apoptosis was revealed in all cases and there was no statistical difference between GCLRS and GCLPS. Immunohistochemical expression for bcl-2 was revealed only in the cytoplasm of lymphocytes in all cases, but bax showed distinct expression in the cytoplasm of neoplastic cells in all cases. There was a significant correlation between bax expression and the apoptotic index (p < 0.05). Lymphocytic infiltration was significantly correlated with the expression of EBV (p < 0.05) but not with survival rate and apoptosis. Most of the GCLRS cases were rated as low clinical stage (stage IA or B) and seemed to have a good prognosis. Conclusions: These results support the hypothesis that EBV infection plays an important role in the tumorigenesis of GCLRS, which has a better prognosis than usual gastric adenocarcinoma although there was no significant difference in the apoptotic index between GCLRS and GCLPS.