Evaluation of plasma Epstein-Barr virus DNA load to distinguish nasopharyngeal carcinoma patients from healthy high-risk populations in Southern China

Abstract

Background: The utility of circulating Epstein-Barr Virus (EBV) DNA as a tumor marker for nasopharyngeal carcinoma (NPC) detection suggests that it might improve the diagnostic performance of anti-EBV antibody markers in NPC screening. In this study, the authors evaluated whether circulating EBV DNA load is capable of distinguishing NPC patients from high-risk individuals who have positive anti-EBV antibodies.

Methods: In a population-based NPC screening trial in Sihui City and Zhongshan City, Guangdong Province, China, the authors previously identified 862 high-risk participants with 2 screening markers, immunoglobulin A (IgA) antibodies to EBV capsid antigen (VCA/IgA) and nuclear antigen-1 (EBNA1/IgA). In the current study, real-time polymerase chain reaction was used to measure the baseline plasma EBV DNA load among 825 participants (97%). Follow-up was extended to the end of 2011 to evaluate the diagnostic and predictive values of plasma EBV DNA load.

Results: By using 0 copies/mL as the cutoff value, plasma EBV DNA had a sensitivity of 86.8% (33 of 38 patients) for NPC detected within the first year of follow-up, yielding a positive predictive value of 30% (33 of 110 participants) and a negative predictive value of 99.3% (696 of 701 participants). The patients who had early stage NPC had lower sensitivity (81.5%; 22 of 27 patients) than those who had advanced NPC (100%; 11 of 11 patients). For the 14 patients who had NPC detected after 1 year of follow-up, only 50% (7 of 14 patients) tested positive for EBV DNA at baseline.

Conclusions: The plasma EBV DNA load may improve the accuracy of diagnosing NPC in high-risk individuals, but it appears to have limited value in screening patients who have early stage NPC and predicting NPC development.

Keywords: Epstein-Barr virus; nasopharyngeal carcinoma; screening; tumor marker; viral load.