Different Clinical Significance of Pre- and Post-treatment Plasma Epstein-Barr Virus DNA Load in Nasopharyngeal Carcinoma Treated with Radiotherapy

Aims: To correlate the pre-treatment plasma Epstein Barr virus (EBV) DNA with tumour burden and to explore the prognostic implications of pre- and post-treatment plasma EBV DNA load in nasopharyngeal carcinoma patients treated with radiotherapy. Materials and methods: Plasma EBV DNA load was measured using a real-time quantitative polymerase chain reaction assay in 69 patients with nasopharyngeal carcinoma before and after radiation treatment and correlated with tumour volume and treatment outcome. Tumour volume was calculated by multiplying the sum of the areas of gross extent of the primary tumour and regional lymph nodes shown by computed tomography images and/or magnetic resonance imaging. Prognostic models for distant metastasis and overall survival were constructed using a multivariable fractional polynomial algorithm. Results: The pre-treatment plasma EBV DNA concentration was significantly associated with tumour volume (Spearman correlation coefficient, 0.61; P < 0.001). The multivariable fractional polynomial algorithm selected post-treatment EBV DNA and administration of chemotherapy as prognostic factors for distant metastasis (P < 0.001, P=0.021, respectively), as well as for overall survival (P < 0.001, P=0.018, respectively). Conclusions: Pre- and post-treatment plasma EBV DNA load have important clinical significance. Pre-treatment plasma EBV DNA concentration reflects tumour burden, whereas clearance of circulating plasma EBV DNA after treatment predicts the risk of distant metastasis and overall survival. (C) 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.