Lymph-node Epstein-Barr virus concentration in diagnosing cervical lymph-node metastasis in nasopharyngeal carcinoma

Purpose Cervical lymph-node (CLN) metastasis commonly occurs in patients with nasopharyngeal carcinoma (NPC) metastasis. The presence of Epstein-Barr virus (EBV) genomes in neck lymph nodes may diagnose CLN. This research was designed to appraise the diagnostic value of EBV concentration for cervical lymph nodes in NPC. Methods Two hundred and fifty-three NPC patients with 276 CLNs were enrolled. MRI was performed to detect CLN metastasis, and plasma EBV concentration was measured by quantitative PCR before treatment. Ultrasonography (US) and US-FNA were subsequently performed in the suspicious lymph nodes. Fifteen patients (22 lymph nodes) underwent fine-needle aspiration cytology (FNAC), and the remaining 242 patients (254 lymph nodes) underwent core needle biopsy (CNB) for CLNs at the clinician's demand. The aspiration needle was rinsed with 1 ml of normal saline for EBV detection. The method of lymph-node EBV measurement was consistent with that for plasma. The MRI results and EBV concentrations in plasma and lymph nodes were recorded and analyzed. Plasma EBV concentrations >= 4000 copies/ml were regarded as positive. Results CLN-EBV concentrations >= 787.5 copies/ml were regarded as positive according to receiver-operating characteristic curve analysis. The AUC of the EBV (0.925) concentration in CLN metastasis was significantly larger than the AUC of MRI (0.714) (P < 0.001). The sensitivity and specificity were 94.09% and 48.72% for MRI in lymph-node metastasis and 95.36% (P > 0.05) and 84.62% (P < 0.01) for EBV DNA in CLN metastasis, respectively. The sensitivity and specificity of EBV in plasma were 77.2% and 71.8%, respectively. The diagnostic specificity and AUC of EBV in CLNs were higher than those of MRI and plasma EBV (P < 0.005). Conclusions Ultrasound-guided CLN FNA to obtain EBV concentrations may provide a new method to diagnose CLN metastasis with high sensitivity and specificity.