Relationship between the Epstein-Barr virus and undifferentiated nasopharyngeal carcinoma: correlated nucleic acid hybridization and histopathological examination.

In order to examine critically the closeness of association between Epstein-Barr virus (EBV) DNA and nasopharyngeal carcinoma (NPC) a correlated histopathological and nucleic acid hybridization study was performed on 51 undifferentiated NPC, 4 NPC with some signs of squamous differentiation, 7 nasophayngeal tumors of other histological types and 14 head and neck carcinomas located outside the nasopharynx. All 51 undifferentiated NPCs contained significant numbers of EBV-genome copies per cell. Two of the somewhat differentiated NPCs were also EBV-DNA-positive, whereas 2 were negative. Of the 7 other nasopharyngeal tumors, 1 was EBV-DNA-positive. Histological examination, however, showed that this was a typical Burkitt lymphoma. The other 6 tumors were all EBV-DNA-negative lymphoproliferative malignancies. All 14 had head and neck carcinomas located outside the nasopharynx were EBV-DNA-negative. The sera of undifferentiated NPC patients had elevated antibody titers against the EBV-determined antigens, the EA (D) componet in particular. These findings confirm that there is a regular association between EBV-DNA and undifferentiated NPC.