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 nasopharyngeal 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 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) component in particular. These findings confirm that there is a regular association between EBV‐DNA and undifferentiated NPC.