Clinicopathological and prognostic features of Epstein‐Barr virus infection, microsatellite instability, and PD‐L1 expression in gastric cancer

Background and Objectives Gastric cancer (GC) has recently been categorized in molecular subtypes, which include Epstein‐Barr (EBV)‐positive and microsatellite instability (MSI) tumors. This distinction may provide prognostic information and identifies therapeutic targets. The aim of this study was to evaluate EBV, MSI, and PD‐L1 immunoexpression in GC and its relationship with clinicopathological characteristics and patient's prognosis. Methods We evaluated 287 GC patients who underwent D2‐gastrectomy through immunohistochemistry for DNA mismatch repair proteins and PD‐L1, and in situ hybridization for EBV detection utilizing tissue microarray. Results EBV‐positive and MSI were identified in 10.5% and 27% of the GCs, respectively. EBV positivity was associated to male gender (P = 0.032), proximal location (P