Peripheral blood quantitative PCR analysis of EBV DNA in nasopharyngeal carcinoma

Abstract

5557 Background: Epstein-Barr virus (EBV) is the major etiology of WHO type 2, 3 nasopharyngeal carcinoma (NPC). Almost every tumor cell contains EBV genome. Correlation between prognosis, disease status and serum EBV DNA level was recently reported. Methods: We conducted a cross-sectional study to determine the correlation between the EBV DNA level from circulating tumor cells and the status of disease. The subjects were classified into 4 groups: new diagnosis, in remission, recurrent disease and control (healthy volunteers). The number of subjects/group was calculated to be at least 32, using proportion of P0 = 40%, P1 = 10% at α = 0.05 and Power = 80%. Genomic DNA was isolated from buffy coat of peripheral blood sample. Using Taqman probes for latent membrane protein 2 (LMP2) gene in EBV genome and beta actin gene as internal control, real-time quantitative PCR was performed. The LMP2 copy number was adjusted according to the beta actin copy number from the same sample. Results: The LMP2 gene can be quantified in the samples from new diagnosis, in remission, recurrent disease and control groups as following: 11/33 (33.3%), 10/29 (34.5%), 19/33 (57.6%) and 0/32 (0%) respectively. Among the patients with measurable LMP2, the median (range) of LMP2 copy numbers of each patient group are 12.97 (1.89–118.41), 18.75 (11.79–92.08) and 38.26 (2.41–642.76) copies/500 ng DNA respectively. Using Chi-Square test, all three patient groups have significantly higher LMP2 copy number than the control group (p < .001). The recurrent disease group has significantly higher LMP2 copy number than the new diagnosis group (p=.048). There is no significant difference between the in remission group and the other patient groups. The sensitivity of this test is 42.1% and the specificity is 100%. Conclusions: The peripheral blood EBV DNA copy number, determined by Real-time quantitative PCR, may be a potential molecular marker in the screening for NPC. No significant financial relationships to disclose.