title: Rapid clearance of plasma Epstein-Barr virus DNA after surgical treatment of nasopharyngeal carcinoma.
abstract: OBJECTIVE
  Circulating EBV DNA analysis has been shown to be valuable in the detection, prognostication, and monitoring of nasopharyngeal carcinoma (NPC) patients. A previous study has shown that, after radiotherapy, plasma EBV DNA levels of NPC patients would decline exponentially with a median half-life of 3.8 days. We postulate that this decline in plasma EBV DNA reflects the decrease in cancer cell population and, therefore, the rate of decline reflects the radiosensitivity of the tumor. However, this postulation would hold true only if EBV DNA is rapidly eliminated from the circulation. In this study, we determined the in vivo elimination rate of plasma EBV DNA in NPC patients.
  
  
  METHODS
  We monitored the level of plasma EBV DNA in NPC patients during and after surgical resection of NPC. The half-life of plasma EBV DNA was then calculated by plotting the natural logarithm of EBV DNA concentrations against time.
  
  
  RESULTS
  The median half-life of plasma EBV DNA after surgical resection of NPC was 139 min. After a median follow-up of 6.7 days, EBV DNA was undetectable in 8 of 11 patients. One of 8 patients with undectable EBV DNA and all of the patients with detectable EBV DNA developed clinical relapse.
  
  
  CONCLUSIONS
  The in vivo elimination of EBV DNA is very rapid after surgical resection of NPC. The failure of complete and rapid elimination of EBV DNA from the circulation predicts disease recurrence.
authors.affiliation: Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong Special Administrative Region, China.
authors.forename: Edward W H
authors.initials: EW
authors.lastname: To
authors.forename: K C Allen
authors.initials: KC
authors.lastname: Chan
authors.forename: Sing-Fai
authors.initials: SF
authors.lastname: Leung
authors.forename: Lisa Y S
authors.initials: LY
authors.lastname: Chan
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.forename: Anthony T C
authors.initials: AT
authors.lastname: Chan
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Johnson
authors.forename: Y M Dennis
authors.initials: YM
authors.lastname: Lo
mesh_terms: D014408:Biomarkers, Tumor; D002277:Carcinoma / Q000601:surgery* / Q000821:virology*; D004279:DNA, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics*; D006801:Humans; D017403:In Situ Hybridization; D007700:Kinetics; D008962:Models, Theoretical; D009303:Nasopharyngeal Neoplasms / Q000601:surgery* / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D014408:Biomarkers, Tumor; D004279:DNA, Viral