Nasopharyngeal brush biopsies and detection of nasopharyngeal cancer in a high-risk population

Background: Nasopharyngeal carcinoma (NPC) is an important tumor in many co untries. Ethnic and regional factors strongly influence disease risk. NPC i s usually diagnosed late in disease development, and 10-year survival rates are as low as 10%. Epstein-Barr virus (EBV), a possibly causative agent, i s present in all cells of essentially all undifferentiated NPCs. We wished to determine the following: 1) whether an ambulatory nasopharyngeal brush b iopsy could provide sufficient tumor cell DNA for the detection of EBV and 2) whether the detection of EBV in this locale reflects the presence of tum or cells or simply EBV carrier status. Methods: We collected nasopharyngeal tissue via ambulatory brush biopsies from 21 patients with newly diagnosed NPC and from 157 subjects with other otolaryngologic complaints. The major ity of study subjects were from highrisk populations. Sample DNA was analyz ed for the presence of EBV genomic sequences by use of the polymerase chain reaction (PCR). Results: Ninety-six percent of samples yielded sufficient DNA for PCR amplification. Nineteen of 21 patients with NPC brushed positiv e for EBV DNA, while all but two (1.3%) of 149 informative control subjects were negative for EBV (two-sided P<.0001). One of the EBV-positive control subjects had an EBV-positive inverted sinonasal papilloma; the other EBV-p ositive control subject exhibited no overt clinical disease. Conclusion: De monstration of EBV DNA in nasopharyngeal brush biopsy specimens detects NPC with a sensitivity of at least 90% (95% confidence interval = 89.63%-91.32 %) and a specificity of approximately 99% (95% confidence interval = 98.64% -98.68%). This technique merits further testing as a possible ambulatory sc reening strategy in high-risk populations.