[Detection of EBV by PCR in fresh and paraffin embedded samples of cavum tumour]

The nasopharyngeal carcinoma (NPC) is frequent in Tunisia. It's the second ORL cancer of men after the larynx one. To analyse the NPC characteristics in our population, we determined the frequency of EBV infection in 47 paraffin-embedded and 6 fresh NPC biopsies. We first extracted the DNA from tumoral tissus and then amplified viral sequences by PCR to detect and to type the infecting virus (EBV-A or ABV-B). Our results showed that amplifiable DNA has been obtained from 34/47 paraffin-embedded NPC biopsies while 13/47 of the others biopsies contained degraded and not amplifiable DNA. All the fresh biopsies allowed to obtain DNA with good quality. The EBV infection frequency in paraffin-embedded NPC biopsies is 35% while EBV is detected in all fresh biopsies (6/6). Our analyse also showed that the EBV-A is predominant in our population compared to EBV-B as it was shown in most countries of the world. This study clearly shows that PCR results obtained with paraffin-embedded NPC biopsies are divergeant from those obtained with fresh biopsies. Because of DNA degradation in paraffin-embedded NPC biopsies, the biology molecular results from that kind of samples is criticable. Moreover the results obtained from fresh NPC biopsies confirmed the quasi-constant association of EBV with undifferenciated carcinoma nasopharyngeal type.