Prevalence of Epstein-Barr virus in oral squamous cell carcinoma.

Forty-six samples of oral squamous cell carcinoma (OSCC) were evaluated for the prevalence of Epstein-Barr virus (EBV) infection by the polymerase chain reaction (PCR), Southern blot hybridization, and in situ hybridization (ISH). EBV DNA was detected in 7 (15.2 per cent) out of 46 samples by a combination of PCR and Southern blot hybridization methods. All seven positive samples showed well-differentiated carcinoma, thus suggesting a possible relationship between EBV infection and the degree of differentiation of carcinoma tissue. Latent infection membrane protein 1 (LMP1) was detected immunohistochemically in six of the EBV-positive OSCCs. However, no signal of the EBV-encoded small RNA (EBER)-1 was demonstrated by the ISH method. No significant relationship was observed between EBV infection and lymph node metastasis. A follow-up study (range from 4.4 to 79 months; mean 34.9 months) showed no recurrence or death to occur in the EBV-positive patients, which thus suggested a good prognosis for EBV-positive OSCC patients.