Detection of cell free Epstein–Barr virus DNA in sera from patients with nasopharyngeal carcinoma

Abstract

BACKGROUNDThe detection of tumor‐derived DNA within the circulation of patients with malignant disease using polymerase chain reaction (PCR)‐based strategies has opened a new avenue for the diagnosis and monitoring of these patients. Because of the universal association of Epstein–Barr virus (EBV) with the nonsquamous type of nasopharyngeal carcinoma (NPC; World Health Organization types II and III), the detection of cell free EBV DNA in sera from patients with NPC may be a valuable tool for monitoring the progress of tumors or to provide advanced warning of tumor recurrence.METHODSSerum samples were obtained from different patients, and cell free EBV DNA was detected with a conventional PCR approach. A total of 134 patients were sampled, including 36 patients with primary NPC, 28 control patients, 18 patients suffering from locoregional recurrence, 7 patients with distant metastasis, and 45 patients with NPC in clinical remission. A conventional PCR approach employing standard 35‐cycle and 50‐cycle reactions was used to detect cell free EBV genomes. Results from the two PCR cycles were compared to provide a semiquantitative picture of the relative quantity of EBV genome in each serum sample.RESULTSThe EBV DNA detection rates, i.e., the rates of positive detection, for 35‐cycle and 50‐cycle PCR analyses, respectively, were 38.9% and 75% for patients with primary NPC, 3.5% and 10.7% for control patients, 27.8% and 88.9% for patients with locoregional disease recurrence, 71.4% and 100% for patients with distant metastasis, and 7.1% and 36.5% for patients with disease in clinical remission. The rates of positive detection among patients with active disease all appeared to be significantly greater compared with the rates among patients with disease in clinical remission. Longitudinal data for six patients with recurrent tumors revealed a close correlation between the relative quantity of circulating cell free EBV genomes and the disease course of these patients. The sensitivity, specificity, positive predictive value, and negative predictive value of the 50‐cycle PCR analysis for detecting recurrent disease were 92%, 63.5%, 42.6%, and 96.4%, respectively.CONCLUSIONSThis study demonstrated that, by using a 50‐cycle PCR‐based approach, high sensitivity and high negative predictive value for detecting recurrent disease can be obtained from the detection of the cell free EBV genome in sera from patients with NPC. The 50‐cycle PCR analysis, therefore, may provide a simple, clinically useful adjuvant method for monitoring patients with NPC. Cancer 2002;94:723–9. © 2002 American Cancer Society.DOI 10.1002/cncr.10251

Quantitative Plasma Hypermethylated DNA Markers of Undifferentiated Nasopharyngeal Carcinoma

“…The sensitivity of EBV DNA was found to be only 38% for rT1 and 50% for rT2 local recurrence after radiotherapy by the same group of investigators recently (14). Low sensitivity (28%) for locoregional NPC recurrence was also reported by Hsiao et al (15), and the increase of PCR cycle can increase the sensitivity to 89% but was also found to increase the false-positive rate to 37%. EBV DNA is, therefore, not a satisfactory marker for locoregional recurrence.…”

“…The sensitivity and specificity of EBV DNA are not duplicative in different laboratories by different investigators, and it was, however, found to have low sensitivity or high false-positive rates in recent reports (12,14,15). The sensitivity of EBV DNA was found to be 56% by Chan et al (12) and is much more inferior than EBV antibodies.…”

“…EBV antibodies are not effective in screening recur-rent NPC. The sensitivity and specificity of plasma EBV DNA, however, was found to be unsatisfactory in screening primary and potentially salvageable local or regional recurrent NPC in more recent studies (12)(13)(14)(15). A better screening tumor marker, which can replace or complement the currently used EBV antibodies or DNA, are desirable.…”

A Comparison Study of Different PCR Assays in Measuring Circulating Plasma Epstein-Barr Virus DNA Levels in Patients with Nasopharyngeal Carcinoma

“…Only 50% of our patients had detectable EBV DNA levels at diagnosis, a result that is similar to those reported for EBNA-1 assays (21). Recently, Hsiao et al showed that an increase in the number of PCR cycles from 35 to 50 cycles during EBNA-1 testing resulted in improved detection sensitivity from 35% to 75% but at the expense of specificity (22). An increase in the number of PCR cycles during Pol-1 testing (from 40 to 50 cycles) may be useful in improving DNA detection rate in these patients.…”

Improved Accuracy of Detection of Nasopharyngeal Carcinoma by Combined Application of Circulating Epstein–Barr Virus DNA and Anti-Epstein–Barr Viral Capsid Antigen IgA Antibody

“…It is conceptually distinct from other peripheral blood markers in that it directly measures tumor-derived EBV genomic material rather than an antibody response to genomic or peptidic components of the EBV. Although initial studies based on qualitative measurement systems showed that plasma EBV DNA has a sensitivity of only 59 -75% for diagnosis of NPC (33)(34)(35), its sensitivity in quantitative assays was as high as 90% (36 ). Such a diagnostic sensitivity appears to be at least as good as that of IgA-VCA, although direct comparative studies of the two markers have yet to be reported.…”