Treatment response and prognosis according to pre and post treatment Ebstein-Barr virus DNA level in nasopharyngeal carcinoma patients.

Abstract

e17544 Background: To evaluate pre and post-treatment Epstein-Barr virus (EBV) DNA copy numbers, to investigate changes with treatment and the possibility of using it as a follow-up marker in nasopharyngeal carcinoma (NPC) patients. Methods: Blood samples were obtained before (0-3 weeks) and after treatment (mean 6 weeks) and number of EBV DNA copies were determined by PCR . Treatment was administered as concomittant chemoradiotherapy ± induction chemotherapy. MRI and PET-CT were performed prior (0-4 weeks) and after (6-16 weeks) treatment. Mann Whitney test was used for 2 group comparisons of parameters with no normal distribution and comparison of quantitative data. Fisher-Freeman-Halton and Wilcoxon Signed Ranks tests were used for comparison of qualitative data and intra-group comparison of parameters with non-normal distribution. Kaplan Meier Survival analysis was used to assess survival. Results: The study included 50 NPC patients treated between 2011 and 2015. Median follow-up is 25.3 (27.5 ± 14) months. 12 patients had residual-recurrent or metastatic (3 patients initially had distant metastasis) disease. Mean survival is 49.77 ± 2.4 months. Median posttreatment EBV DNA level is lower than pretreatment EBV DNA level (p = 0.001). Pretreatment EBV DNA copy numbers are higher in patients with residual-recurrent or metastatic disease (RRM) than those without RRM (p=0.05). Mortal patients had higher pre (p = 0.015) and post (p = 0.043) treatment EBV DNA levels than those who survived. Overall survival (OS) is higher in patients with undetectable (n:41) than those with detectable (n:9) EBV DNA levels after treatment (p = 0.02). Conclusions: The OS is lower in patients with higher pretreatment and detectable posttreatment EBV DNA levels. This study implies that pre and post treatment serum EBV DNA levels can be used as prognostic indicators and also be beneficial as a follow up marker in NPC patients. [Table: see text]