Epstein-Barr virus DNA in nasopharyngeal carcinoma in Thai patients at Ramathibodi Hospital, Bangkok.

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in Thailand. The association of Epstein-Barr virus (EBV) and NPC, especially undifferentiated type, has been documented. There is, however, conflicting evidence with regard to the squamous cell type. We have therefore investigated EBV-DNA in all the three types of NPC to assess the association of EBV and NPC in Thai patients. EBV-DNA was detected in formalin-fixed paraffin-embedded tissues from the patients of Ramathibodi Hospital, Bangkok using polymerase chain reaction. A primer pair that amplified EBV nuclear antigen gene was used in the reactions and the amplification products were hybridized with a specific EBV probe. EBV-DNA was identified in 24 of 28 of tissue samples from patients with undifferentiated NPC, 25 of 40 samples from patients with squamous cell NPC and 3 of 4 samples with nonkeratinizing NPC. None of 12 nasopharyngeal tissue samples without NPC contained detectable EBV-DNA. Our results indicated a strong association of EBV with undifferentiated as well as non-keratinizing NPC. EBV-DNA was demonstrated in most cases of squamous cell NPC but the association of EBV in this type of carcinoma was not as frequent as in the other two types of NPC.