Epstein-Barr virus DNA measured in nasopharyngeal brushings in patients with nasopharyngeal carcinoma: pilot study

OBJECTIVE: We measured the amount of tumour-derived Epstein-Barr virus (EBV) deoxyribonucleic acid (DNA) in the nasal brushings of nasopharyngeal carcinoma (NPC) patients to determine the correlation with tumour load and response to treatment. MATERIALS AND METHODS: Twenty-eight patients with NPC were included in the study. Baseline measurements of EBV from nasopharyngeal brushings were obtained from 26 patients prior to treatment. A follow-up sample was available from 11 of these patients post-treatment and from 2 additional patients who did not have a baseline sample. Quantitative real-time polymerase chain reaction (PCR) using SYBR Green I fluorescent dye was used to detect the EBV DNA copy number. RESULTS: Nasopharyngeal brush biopsies showed a high copy number of EBV DNA in most of the pretreatment samples (median 9714 copies/mL). The highest copy number detected was 14536944 copies/mL in one sample. In the post-treatment follow-up samples, the copy number was significantly lower (median 6 copies/mL). CONCLUSIONS: We have demonstrated that EBV DNA can be detected in the brush biopsies from NPC patients using quantitative real-time PCR. These pilot data suggest that nasopharyngeal brushings with PCR detection of EBV may be an effective tool for determining local tumour response. The potential of this technique as an NPC tumour marker for post-treatment follow-up is being validated with larger patient numbers.