Prognostic effect of residual plasma Epstein-Barr viral DNA after induction chemotherapy for locoregionally advanced nasopharyngeal carcinoma.

Abstract

To assess the prognostic effect of plasma Epstein-Barr virus (EBV) DNA load after induction chemotherapy (postIC -EBV DNA) on survival outcomes in locoregionally advanced nasopharyngeal carcinoma (LA-NPC). Patients who were diagnosed with LA-NPC between August 2017 and October 2021 were included. The chi-squared test, receiver operating characteristic, Kaplan-Meier survival analysis, and Cox proportional hazard model were used for statistical analysis. We included 172 patients with EBV DNA-positive LA-NPC in this study. There were 35.5% (n = 61) of patients had plasma residual EBV DNA after induction chemotherapy (IC). Patients with higher EBV DNA before IC (p < 0.001) and advanced nodal stage (p = 0.031) were significantly related to a higher rate of residual postIC -EBV DNA. Patients with detectable postIC -EBV DNA had inferior 3-year locoregional relapse-free survival (LRFS) (86.7% vs. 96.9%, p = 0.020), distant metastasis-free survival (DMFS) (76.8% vs. 94.2%, p < 0.001), disease-free survival (DFS) (68.2% vs. 91.1%, p < 0.001), and overall survival (OS) (87.8% vs. 97.9%, p = 0.044) compared to those with undetectable postIC -EBV DNA. The multivariate prognostic analyses showed that detectable postIC -EBV DNA was the independent prognostic factor related to LRFS (p = 0.032), DMFS (p = 0.010), and DFS (p = 0.004) than those with undetectable postIC -EBV DNA. Pretreatment EBV DNA load had no prognostic effect in the multivariate analyses. The monitoring of plasma postIC -EBV DNA has improved prognostication in LA-NPC. Our findings suggest that postIC -EBV DNA may be a robust indicator to identify the optimal candidate for intensive treatment.