title: Evaluation of plasma Epstein-Barr virus DNA load as a prognostic marker for nasopharyngeal carcinoma.
abstract: BACKGROUND
  Nasopharyngeal carcinoma (NPC) is an important cancer in Malaysia and is one of the major causes of cancer mortality in this country. This study evaluates the diagnostic and prognostic values in the quantitative relationship between the cell-free Epstein-Barr virus (EBV) deoxyribonucleic acid (DNA) load and the tumour burden.
  
  
  METHODS
  Blood plasma from 18 untreated NPC patients, 20 NPC patients who had been treated with radiotherapy, and 12 healthy individuals were evaluated. EBV copy number was determined following DNA extraction using real-time quantitative polymerase chain reaction.
  
  
  RESULTS
  The cell-free EBV DNA load was shown to be proportionately related to the presence of malignant disease. While the EBV copy number in untreated NPC patients had a median of 2,043 copies/ml, viral load in plasma of healthy controls was significantly lower (median of 0 copy/ml). A significant decrease in EBV load was observed in patients who had undergone radiotherapy while a high viral load indicated in one patient correlated to tumour relapse and presence of distant metastasis upon clinical investigation.
  
  
  CONCLUSIONS
  The blood plasma EBV DNA load was shown to be proportionately related to the presence of malignant disease. This preliminary study underscores the prognostic value of cell-free EBV DNA quantification.
authors.affiliation: Department of Pharmacy and Health Sciences, International Medical University, Plaza Komanwel, Bukit Jalil, Kuala Lumpur 57000, Malaysia. englaitan@gmail.com
authors.forename: E L
authors.initials: EL
authors.lastname: Tan
authors.forename: L M
authors.initials: LM
authors.lastname: Looi
authors.forename: C K
authors.initials: CK
authors.lastname: Sam
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis / Q000097:blood; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D004279:DNA, Viral / Q000097:blood*; D020031:Epstein-Barr Virus Infections / Q000097:blood / Q000150:complications* / Q000821:virology; D004854:Herpesvirus 4, Human / Q000235:genetics*; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000821:virology; D016133:Polymerase Chain Reaction; D011379:Prognosis; D019562:Viral Load
chemical_list: D014408:Biomarkers, Tumor; D004279:DNA, Viral