EBV infection and MSI status significantly influence the clinical outcomes of gastric cancer patients

Background Epstein-Barr virus (EBV) and microsatellite instability (MSI) are associated with the carcinogenesis of many kinds of tumors, including gastric cancer (GC). However, the impact of EBV and MSI status on the prognosis of stage II and III GC is still unclear. The aim of this study was to find out the prognostic value of EBV and MSI status in a population of GC patients from Southern China. Methods Patients were genotyped for EBV infection based on the detection of EBV DNA from the formalin-fixed paraffin-embedded (FFPE) specimens. Sequentially, MSI status was measured by direct sequencing. Clinical characteristics and overall survival (OS) were analyzed in 202 GC patients. Additionally, the association of EBV and MSI status with chemotherapy-based toxicity was analyzed in 324 GC patients. Results The survival analysis revealed EBV + patients had a poorer OS than EBV − patients (HR = 1.75, 95% CI: 1.08–2.82, FDR p = 0.04). This survival advantage for EBV − patients was also found in patients p = 0.04) and patient with stage III disease (FDR p = 0.04). Conclusions EBV infection and MSI status are associated with overall survival of gastric cancer patients. However, traditional chemotherapy showed no difference on outcome of patients in EBV and MSI subgroups.