The diagnostic and prognostic values of plasma Epstein-Barr virus DNA for residual cervical lymphadenopathy in nasopharyngeal carcinoma patients: a retrospective study

BACKGROUND: Currently, the diagnosis and treatment of nasopharyngeal carcinoma (NPC) patients with residual cervical lymphadenopathy following radical radiotherapy with or without chemotherapy are challenging. We investigated the prognosis of NPC patients with residual cervical lymphadenopathy and assessed the diagnostic and prognostic values of Epstein-Barr virus (EBV) DNA in these patients. METHODS: This study included 82 NPC patients who were diagnosed with suspected residual cervical lymphadenopathy following completion of antitumor therapy. Their plasma EBV DNA levels were measured using quantitative polymerase chain reaction (qPCR) before the initiation of treatment and before neck dissection. Fine needle aspiration cytology (FNAC) was performed in 21 patients. All patients had undergone neck dissection and postoperative pathological examination to identify the nature of residual cervical lymphadenopathy. The overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS), and locoregional relapse-free survival (LRRFS) were calculated using the Kaplan–Meier method and compared using the log-rank test. The Cox proportional hazards model was used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). Multivariable analysis was used to estimate the effect of potential prognostic factors on survival. RESULTS: Following a median follow-up of 52.6 months, compared with patients with negative postoperative pathological findings for residual cervical lymphadenopathy, the patients with positive findings had a significantly lower 3-year PFS rate (49.9% vs. 83.3%, P = 0.008). Among NPC patients with residual cervical lymphadenopathy, the patients with preoperative plasma EBV DNA > 0 copy/mL had a lower 3-year PFS rate than did those with no detectable EBV DNA (43.7% vs. 61.1%, P = 0.031). In addition, combining FNAC with preoperative EBV DNA detection improved the diagnostic sensitivity. Multivariable analysis demonstrated that residual cervical lymphadenopathy with positive postoperative pathological result was an independent prognostic factor for PFS and that detectable preoperative plasma EBV DNA was an independent prognostic factor for OS. CONCLUSIONS: Using FNAC combined with preoperative EBV DNA detection improves the sensitivity in diagnosing NPC with residual cervical lymphadenopathy. Compared with patients with undetectable EBV DNA, patients with detectable preoperative plasma EBV DNA have worse prognosis and may require a more aggressive treatment strategy.