You R, et al. - Among prospectively enrolled 148 metastatic nasopharyngeal carcinoma (mNPC) patients, researchers assessed the number of circulating tumor cells (CTCs) and Epstein–Barr virus DNA (EBV DNA) for diagnosis, monitoring and prognosis of this disease condition. At baseline and following first-line chemotherapy, levels of CTCs and EBV DNA were measured. The criteria of having CTC of 12 at baseline and 1 after first-line chemotherapy and EBV DNA of 10,000 at baseline and 4,000 after first-line chemotherapy, were used to stratify patients into unfavorable and favorable prognostic groups, respectively. Significantly longer progression-free survival and overall survival were observed in relation to conversion of baseline unfavorable CTCs and EBV DNA to favorable following first-line chemotherapy vs patients with unfavorable CTCs and EBV DNA at both time points. For mNPC patients, strong predictive markers were the number of CTCs and EBV DNA before, after and during first-line chemotherapy. Additional prognostic information could be gained by utilizing CTCs and EBV DNA in conjunction with imaging studies.