Because the EBV DNA load before treatment has been recognized as a marker of tumor burden and disease stage (T and N stage) as quantified by MRI and FDG-PET [19], [20], the correlation of concentrations between the CXCL9 and EBV DNA load in circulation was also analyzed to investigate their potential association with NPC tumor burden and EBV. This evidence concerns the gene CXCL9 and nasopharyngeal carcinoma.