Prognostic value of tumor infiltrating lymphocytes in Epstein-Barr virus-associated gastric cancer.

4062 Background: It is well known that lymphocytic infiltration around tumor can be considered as a host immune reaction against tumor cells, although prognostic implication of lymphocyte infiltration in gastric cancer are not certain. Therefore, we investigated prognostic impact of tumor-infiltrating lymphocytes (TILs) in Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC), which can be sub-classified into 3 histological subtypes according to the host immune response: lymphoepithelioma-like carcinoma (LELC), carcinoma with Crohn’s disease-like lymphoid reaction (CLR), and conventional-type adenocarcinoma (CA). Methods: In situ hybridization for EBV positivity was performed in 1318 cases that underwent surgery or endoscopic submucosal dissection at Kyungpook National University Hospital between January 2011 and November 2014. Histopathologic analysis of percentage of TILs was performed on hematoxylin and eosin–stained sections. TILs were defined as the percentage of tumor stroma containing infiltr...