NASOPHARYNGEAL SWAB AND PCR FOR THE SCREENING OF NASOPHARYNGEAL CARCINOMA IN THE ENDEMIC AREA - A GOOD SUPPLEMENT TO THE SEROLOGIC SCREENING

Background. Nasopharyngeal carcinoma (NPC)isa common head and neck can cer in Taiwan. Early detection is the best way to improve survival for this disease. A prospective study was designed to assess the feasibil ity of a new screening method for NPC by use of polymerase chain react ion (PGR) based on the close association of NPC and Epstein-Barr virus (EBV). Methods. One hundred thirty-three different tissues from nasop harynx, nose, and sinus were investigated by use of PGR to check for t he presence of EBV genome. Subsequently, from April 1996 to March 1997 , 55 patients were enrolled in a prospective screening study. All pati ents underwent nasopharyngeal swabs before biopsy. Polymerase chain re action detection of EBV genome was conducted on swab samples. Anti-EBV viral capsid antigen (VCA) in IgA and IgG class were checked at the s ame visit. Results. The EBV genome was present in 91.4% (85/93) of NPC tissues and in 25.0% (10/40) of non-NPC tissues (p <.001, chi(2) test ). Of the 55 swabs, 49 (89.1%) specimens obtained enough cells for PCR examination. Thirty of these 49 patients were pathologically proved N PC. The presence of EBV were 86.7% (26/30) in NPC group and 42.1% (8/1 9) in non-NPC group. The sensitivity and specificity were 86.7% and 57 .9%, respectively, which were similar to those of serologic method (87 .5% and 43.5%) when the cut-off point was set at anti-VCA IgG greater than or equal to 160 and IgA greater than or equal to 10. Combining bo th methods elevates the specificity to 84.2%. Conclusions. The sensiti vity of this PCR screening method is similar to that of the serologic method. Combining both methods can greatly increase the specificity, i ndicating this new method is a good supplement to the serologic screen ing of this endemic disease. (C) 1998 John Wiley & Sons, Inc.