Comparative analysis of Epstein-Barr virus (EBV) detection by nested-PCR and non-isotopic in situ hybridization in nasopharyngeal carcinoma (NPC).

The aims of this study were two-fold: first, to assess the relative diagnostic performance of non-isotopic in situ hybridization (ISH) and the nested polymerase chain reaction (nested-PCR) applied to Epstein-Barr virus (EBV) detection in a series of 55 unselected nasopharyngeal carcinoma (NPC) cases and, secondly, to correlate these data with histopathological classification. Our study shows that in 76.36% of NPC cases positive nuclear signals were observed using EBV-ISH. Overall, EBV-ISH positivity varied according to histological type, in that undifferentiated carcinomas showed a higher proportion of positive cases than differentiated cell carcinomas, although ISH results do not show significant differences in relation to histological types when employing two different schemes (WHO and Micheau). However, in adequate quality DNA samples (54 NPC cases), EBV-DNA was detected in 100% of cases using a nested-PCR, supporting the previous view that all histological types of NPC are in reality variants of EBV-infected neoplasia. ISH-negative cases probably reflect a lower sensitivity than PCR, particularly when a small number of viral copies are present, as well as a variable technical effectiveness for detected EBV, independent of the NPC histological type.