ABSTRACT
Objective To explore the correlation between EBV DNA load and peripheral immune cells (including lymphocyte supsets and natural killer cells) before treatment in patients with NPC, and analyze the influence of circulating immune cell supsets related to EBV on the prognosis of NPC patients. Methods We retrospectively analyzed the general data of 203 NPC patients without distant metastasis at the first treatment, as well as the data of peripheral blood EBV DNA and circulating immune cell supset. The ROC curve analysis was used to determine the cutoff value of each circulating immune cell supset. Kaplan-Meier method was used for survival analysis, and Cox regression model was used for multi-factor prognostic correlation analysis. Results The 3-year OS, PFS, DMFS and LRFS of EBV DNA < 400 copies/ml group and EBV DNA≥400 copies/ml group were 99.2% vs. 90.1% (P=0.001), 96.7% vs. 90.1% (P=0.028), 98.4% vs. 90.1% (P=0.005) and 98.4% vs. 100% (P > 0.05), respectively. EBV DNA is negatively correlated with the ratio of CD19+ B cells before treatment (r=-0.138, P=0.040), and there was no significant correlation between EBV DNA and other circulating immune supgroups (P > 0.05). ROC analysis showed that the cut-off value of CD19+B cell ratio before treatment related to the 3-year OS was 8.33% (P=0.02). The 3-year OS, PFS, DMFS and LRFS of patients with CD19+B cells ratio ≤8.33% and CD19+B cells ratio > 8.33% were respectively 90.4% vs. 99.2% (P=0.003), 89.2% vs. 97.5% (P=0.008), 90.4% vs. 98.3% (P=0.008) and 98.8% vs. 99.2% (P > 0.05). However, ROC analysis showed that there was no significant correlation between OS and other peripheral immune cells (including the proportion of CD3+T, CD3+CD4+T, CD3+CD8+T and CD56+NK cells and CD4+/CD8+ ratio). Multivariate analysis showed that EBV DNA load was an independent prognostic factor of 3-year PFS of NPC patients, and the ratio of CD19+B cells was an independent prognostic factor of 3-year PFS, MFS and OS of NPC patients. Conclusion Before treatment, there is a negative correlation between plasma EBV DNA and the proportion of CD19+B cells in peripheral blood. Both can be used as the predictors of 3-year OS, PFS and DMFS of NPC patients.