Noninvasive diagnosis of nasopharyngeal carcinoma: nasopharyngeal brushings reveal high Epstein-Barr virus DNA load and carcinoma-specific viral BARF1 mRNA.

Nasopharyngeal carcinoma (NPC) is the most prevalent ENT-tumour in Indonesia. We investigated the primary diagnostic value of Epstein-Barr virus (EBV) DNA load and mRNA detection in noninvasive nasopharyngeal (NP) brushings, obtained prospectively from consecutive Indonesian ENT-patients with suspected NPC (N=106) and controls. A subsequent routine NP biopsy was taken for pathological examination and EBER-RISH, yielding 85 confirmed NPC and 21 non-NPC tumour patients. EBV DNA and human DNA load were quantified by real-time PCR. NP brushings from NPC patients contained extremely high EBV DNA loads compared to the 88 non-NPC controls (p<0.0001). Using mean EBV DNA load in controls plus 3 SD as cut-off value, specificity, sensitivity, positive and negative predictive values were 98, 90, 97 and 91%, respectively. Epstein-Barr nuclear antigen 1 (EBNA1) and the carcinoma-specific BARF1 mRNA were detected by nucleic acid sequence based amplification and found in 86 and 74% of NP brushings, confirming NPC tumour cell presence. EBV RNA positivity was even higher in fresh samples stored at -80 degrees C until RNA expression analyses (88% for both EBNA1 and BARF1). EBV RNA-negative NP brushings from proven NPC cases had the lowest EBV DNA loads, indicating erroneous sampling. No EBV mRNA was detected in NP brushings from healthy donors and non-NPC patients. In conclusion, EBV DNA load measurement combined with detection of BARF1 mRNA in simple NP brushings allows noninvasive NPC diagnosis. It reflects carcinoma-specific EBV involvement at the anatomical site of tumour development and reduces the need for invasive biopsies. This procedure may be useful for confirmatory diagnosis in large serological NPC screening programs and has potential as prognostic tool.

Diagnostic value of measuring Epstein-Barr virus (EBV) DNA load and carcinoma-specific viral mRNA in relation to anti-EBV immunoglobulin A (IgA) and IgG antibody levels in blood of nasopharyngeal carcinoma patients from Indonesia.

Nasopharyngeal carcinoma (NPC) is a prevalent malignancy in Southeast Asia and is strongly associated with Epstein-Barr virus (EBV). We investigated the primary diagnostic value of circulating EBV DNA and anti-EBV immunoglobulin G (IgG) and IgA levels in Indonesian NPC patients (n = 149). By a 213-bp Epstein-Barr virus nuclear antigen 1 (EBNA1)-based real-time LightCycler PCR, 72.5% of patients were positive for EBV DNA in whole blood, with 29.5% having levels above a previously determined clinical cutoff value (COV) of 2,000 EBV DNA copies/ml, the upper level in healthy carriers. In a 99-bp LightCycler PCR, 85.9% of patients were positive and 60.4% had levels above the COV. This assay quantified a significantly higher EBV load than the 213-bp PCR assay (P < 0.0001), suggesting that circulating EBV DNA is fragmented. Using data from 11 different studies, we showed a significant inverse correlation between PCR amplicon size and the percentage of patients positive for circulating EBV DNA (Spearman's rho = -0.91; P < 0.0001). EBV DNA loads were unrelated to anti-EBV IgG or IgA levels, as measured by VCA-p18 and EBNA1-specific synthetic peptide-based enzyme-linked immunosorbent assays. The presence of circulating tumor cells was assessed by amplification of BamHI-A rightward frame 1 (BARF1) mRNA, a viral oncogene abundantly expressed in EBV-carrying carcinomas but virtually absent from EBV-associated lymphomas. Despite high EBV DNA loads and the presence of EBNA1 and human U1A small nuclear ribonucleoprotein mRNA, BARF1 mRNA was never detected in blood. We conclude that amplicon size significantly influences EBV DNA load measurement in NPC patients. The circulating EBV DNA load is independent of serological parameters and does not reflect intact tumor cells. The primary diagnostic value of the EBV DNA load for the detection of NPC is limited.