Plasma Epstein-Barr viral deoxyribonucleic acid quantitation complements tumor-node-metastasis staging prognostication in nasopharyngeal carcinoma

Purpose To evaluate the effect of combining circulating Epstein-Barr viral (EBV) DNA load data with TNM staging data in pretherapy prognostication of nasopharyngeal carcinoma (NPC). Patients and Methods Three hundred seventy-six patients with all stages of NPC were studied. Pretreatment plasma/ serum EBV DNA concentrations were quantified by a polymerase chain reaction assay. Determinants of overall survival were assessed by multivariate analysis. Survival probabilities of patient groups, segregated by clinical stage (I, II, III, or IV) alone and also according to EBV DNA load (low or high), were compared. Results Pretherapy circulating EBV DNA load is an independent prognostic factor for overall survival in NPC. Patients with early-stage disease were segregated by EBV DNA levels into a poor-risk subgroup with survival similar to that of stage III disease and a good-risk subgroup with survival similar to stage I disease. Conclusion Pretherapy circulating EBV DNA load is an independent prognostic factor to International Union Against Cancer (UICC) staging in NPC. Combined interpretation of EBV DNA data with UICC staging data leads to alteration of risk definition of patient subsets, with improved risk discrimination in early-stage disease. Validation studies are awaited.