DETERMINATION OF NONENDEMIC NASOPHARYNGEAL CARCINOMA BY IN-SITU HYBRIDIZATION FOR EPSTEIN-BARR-VIRUS EBER1 RNA - SENSITIVITY AND SPECIFICITY IN CERVICAL NODE METASTASES

After time-consuming and costly investigations, patients with neck met astases from an occult primary often receive unnecessarily large radia tion volumes tb treat a possible origin in the nasopharynx, In this st udy a colorimetric antisense Epstein-Barr early ribonucleoprotein 1 (E BER1) oligonucleotide probe specific for Epstein-Barr virus RNA was hy bridized in situ to metastatic tissue obtained from 18 nasopharyngeal, 54 oral and pharyngeal, and 12 occult carcinomas derived from an unse lected population. Ah 16 nonkeratinizing nasopharyngeal carcinomas (NP Cs) were positive for EBER1, Both cases of keratinizing NPC and all 54 other metastases were negative, A single positive case of occult carc inoma indicated its origin from NPC. In retrospect, 7 patients with oc cult carcinoma had received unnecessary treatment with irradiation to the nasopharynx. Nasopharyngeal carcinoma appears to be a less common origin of occult carcinoma than previously considered. In the proper c linicopathologic context EBER1 in situ hybridization (EBER1-ISH) allow s exclusion of NPC with a high degree of accuracy. Thus unnecessarily large radiation volumes and their adverse sequelae may be reduced in t he treatment of occult carcinoma, Conversely, a positive result of ISH allows exclusion of further extensive diagnostic procedures,