e17543 Background: To investigate the relationship between pretreatment Epstein-Barr virus (EBV) DNA copy number and tumor metabolic activity, TNM stage and tumor volume in nasopharyngeal cancer (NPC) patients. Methods: Blood samples were collected 0-3 weeks before treatment and number of EBV DNA copies were determined by PCR . MRI and PET-CT were performed 0-4 weeks before treatment. The primary tumor volume (TVnp) and total volume of metastatic lymph nodes (TLV) were delineated separately on MRI by the same radiologist by the aid of program “Osirix” and recorded in cm3. Maximum SUV values of primary tumor (Tsuv) and metastatic lymph nodes (LNsuv) were determined with each PET-CT images. Kruskal Wallis test and Spearman's Correlation Analysis were used for the comparison of 3 or more groups with no normal distribution and the evaluation of the inter-parameter relations, respectively. Results: The study included 50 NPC patients treated between 2011 and 2015. There was no significant relation between serum EBV DNA copy number and the distribution of T stage (p = 0.81), N stage (p = 0.08), TVnp (r:0.009; p = 0.95), and Tsuv (r:-0.007, p = 0.96). However, a significant correlation was detected between EBV DNA copy number and both LNsuv (r:0.337; p = 0.017) and TLV (r:0.579; p = 0.001) (LNsuv and TLV increased as virus load increased). Conclusions: There is no significant relation between pretreatment EBV DNA load and T and N stages and TVnp in NPC patients. However, EBV DNA load has a significant correlation with TLV and LNsuv. These results may imply that TLV can be included in nodal staging and together with LNsuv be integrated in treatment planning.[Table: see text] [Table: see text]