Contrasted frequencies of p53 accumulation in the two age groups of North African nasopharyngeal carcinomas.

EBV-associated nasopharyngeal carcinomas (NPCs) from Southeast Asia and North Africa have many common clinical and biological characteristics. However, they differ with regard to their age distribution. In Asia, NPC mainly affects patients in the 4th or 5th decade of their life, whereas in North Africa an additional peak of incidence is found between the ages of 10 and 20. The p53 gene is rarely mutated in NPC. However, several groups have reported a consistent accumulation of p53 in Asian NPCs. To determine whether p53 was also accumulated in North African NPCs, we investigated its expression, by immunohistochemistry, in a series of 90 Tunisian biopsies. Bc12 and CD95, two proteins involved in the regulation of cell survival and apoptosis, were investigated in the same study. We found accumulation of p53 in 81% of the cases for patients over 30 years of age, but in only 38% of specimens for younger patients (P = 0.00013). There was a trend toward a higher frequency of Bc12 detection in patients over 30, but it was not statistically significant. CD95 expression was detected in all biopsies, generally at a high level, even at advanced stages of the disease. The changing frequency of p53 accumulation, below and over 30, suggests that NPC cells often achieve malignant transformation through different pathways in both age groups.