The value of plasma EBV DNA in monitoring the therapeutic effect of nasopharyngeal carcinoma

Objective To investigate the clinical value of plasma EBV DNA in monitoring clinical efficacy in the treatment of nasopharyngeal carcinoma (NPC). Methods Clinical data of 799 patients initially diagnosed with NPC treated with radical intensity-modulated radiotherapy (IMRT) in our hospital from 2016 to 2017 were analyzed retrospectively. Prior to treatment, the correlation between plasma EBV DNA, clinical stage and tumor progression was analyzed. The relationship between EBV DNA and tumor progression was analyzed after radiotherapy and during follow-up. Results Before IMRT, the level of EBV DNA was positively correlated with both clinical stage and tumor progression (both P<0.001). At 6 to 8 weeks after IMRT, 19(2.3%) patients positive for plasma EBV DNA obtained the worst prognosis and 14 cases had tumor progression. At 6-8 weeks after IMRT, 9 patients were negative for EBV DNA and 3 cases had tumor progression. The tumor progression rate of patients with undetectable plasma EBV DNA at the end of IMRT was only 8.3%(64/772), and the progression-free survival rate significantly differed among three groups (all P<0.05). The sensitivity, specificity and accuracy rates of persistent positive plasma EBV DNA during follow-up were calculated as 77.6%, 100% and 98.1%, respectively. Conclusions The level of plasma EBV DNA in patients with NPC is correlated with tumor bearing and tumor progression prior to IMRT. At 6-8 weeks after IMRT, patients who are persistently positive for EBV DNA obtain the worst prognosis and should be given with appropriate adjuvant therapy. The correlation between persistent positive plasma EBV DNA during follow up and tumor progression yields a high accuracy rate, indicating that plasma EBV DNA is a reliable biomarker for monitoring the clinical efficacy after radical treatment for NPC patients. Key words: Nasopharyngeal neoplasm/intensity-modulated radiotherapy; EBV; DNA; Monitoring