Correlation of microsatellite status and EBV infection with clinical characteristics of patients with gastric cancer.

This study was designed to investigate the correlation of microsatellite status (MS) and Epstein-Barr virus (EBV) infection with the clinical characteristics of gastric cancer (GC) patients. MS was detected by immunohistochemistry. EBV was detected by in situ hybridization. There were 31.3% cases showed mismatch repair-deficient (dMMR)/ microsatellite instability (MSI) and 68.7% cases showed mismatch repair-proficient (pMMR)/ microsatellite stability (MSS). The dMMR/MSI was more common in the elderly, in patients with cardia GC, smaller tumor diameter or non-poorly differentiated carcinoma. The survival in dMMR/MSI patients tended to be longer than that in pMMR/MSS patients. Total 7.6% cases showed EBV-positive (EBV(+)) among 198 GC patients. EBV(+) was more common in patients with advanced GC or poorly differentiated adenocarcinoma. MSI was more common in EBV-negative (EBV(-)) patients than in EBV(+) patients. The dMMR/MSI patients with stage II GC benefited from chemotherapy. The survival of EBV(+) patients tended to be longer than that of EBV(-) patients.