title: Quantitative analysis of plasma cell-free Epstein-Barr virus DNA in nasopharyngeal carcinoma after salvage nasopharyngectomy: a prospective study.
abstract: BACKGROUND
  The quantity of circulating cell-free Epstein-Barr virus (EBV) DNA in patients with nasopharyngeal carcinoma (NPC) managed by radiotherapy has prognostic relevance. We measured the copy number of EBV DNA in patients with early recurrent NPC before and after salvage nasopharyngectomy.
  
  
  METHODS
  Nasopharyngectomy with the maxillary swing approach was performed for 28 patients. Serum blood samples were taken prospectively before nasopharyngectomy and on postoperative day 7. Plasma cell-free EBV DNA copies were measured with a real-time quantitative polymerase chain reaction for the BamHI-W fragment of the EBV genome.
  
  
  RESULTS
  Cell-free EBV DNA was detected in 17 patients before nasopharyngectomy. Surgical resection reduced the copy number of EBV DNA significantly (p = .016). Negative surgical margins achieved during nasopharyngectomy is associated with a zero EBV DNA copy postoperatively (p = .022).
  
  
  CONCLUSIONS
  Cell-free EBV DNA was detected in 61% of patients with recurrent NPC, and its quantity postoperatively reflects whether the salvage nasopharyngectomy has achieved a negative surgical margin.
authors.affiliation: Division of Head Neck Surgery, Department of Surgery, University of Hong Kong Medical Centre, Queen Mary Hospital, Hong Kong SAR, China. hrmswwi@hkucc.hku.hk
authors.forename: William I
authors.initials: WI
authors.lastname: Wei
authors.forename: Anthony P W
authors.initials: AP
authors.lastname: Yuen
authors.forename: Raymond W M
authors.initials: RW
authors.lastname: Ng
authors.forename: W K
authors.initials: WK
authors.lastname: Ho
authors.forename: Dora L W
authors.initials: DL
authors.lastname: Kwong
authors.forename: Jonathan S T
authors.initials: JS
authors.lastname: Sham
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000532:radiotherapy / Q000601:surgery / Q000821:virology*; D004279:DNA, Viral / Q000097:blood*; D020031:Epstein-Barr Virus Infections / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D004854:Herpesvirus 4, Human / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy / Q000601:surgery / Q000821:virology*; D009305:Nasopharynx / Q000601:surgery; D009364:Neoplasm Recurrence, Local / Q000601:surgery / Q000821:virology*; D010611:Pharyngectomy / Q000379:methods; D016133:Polymerase Chain Reaction; D011379:Prognosis; D011446:Prospective Studies; D016879:Salvage Therapy
chemical_list: D004279:DNA, Viral