The Predictive Value of Epstein-Barr Virus-Positivity in Patients Undergoing Gastrectomy Followed by Adjuvant Chemotherapy

The present study evaluated the survival impact of standard adjuvant chemotherapy and prognostic differences between Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) and EBV-negative gastric cancer (EBVnGC). A total of 276 patients were enrolled according to the following criteria: 1) pathologically diagnosed with primary gastric adenocarcinoma, 2) test results from EBV-encoded RNA in situ hybridization, 3) stage II/III according to the 7th edition of UICC/AJCC staging system for gastric cancer, and 4) postoperative adjuvant chemotherapy. Fifty-nine (21.4%) and 217 (78.6%) patients exhibited EBVaGC and EBVnGC, respectively, while 129 (46.7%) patients were classified as stage II and 147 (53.3%) as stage III. As for adjuvant chemotherapy, 87 (31.5%) patients received capecitabine and oxaliplatin, while 189 (68.5%) received S-1 monotherapy. With a median follow-up duration of 21.3 (6.4-89.0) months, the estimated 3-year disease-free survival (DFS) and overall survival (OS) rates were 74.8% and 83.0%, respectively. In univariate analysis and multivariate analysis using a Cox proportional hazard model including age, gender, stage, Lauren classification, and the type of chemotherapy, EBV-positivity was not significantly associated with DFS (p-value= 0.630) regardless of the type of chemotherapy. Therefore, no association was found between EBV positivity and the survival outcomes in patients with curatively resected gastric cancer who received standard adjuvant chemotherapy.