Expression and mutations of p53 in salivary gland tumours

A series of 219 salivary gland tumours (103 carcinomas and 116 benign tumours) were analysed for p53 protein expression using immunohistochemistry, and for mutations in p53 gene using non-radioactive single strand conformation polymorphism (SSCP). p53 expression was present in 36% (42/116) of the benign tumours and in 54% (56/103) of the carcinomas. The highest prevalence of p53 expression was found in adenoid cystic carcinomas (69%), followed by mucoepidermoid carcinomas (67%). Of the benign tumours, pleomorphic adenomas showed the highest prevalence of p53 positivity (41%). In malignant tumours, expression of p53 bore no correlation to local recurrence, metastatic disease or survival of the patients. Exons 5 through 9 were analysed and four mutations were found in 20 cases of p53-immunopositive tumours and two in 20 p53-negative tumours. Each of the exons 5, 6 and 8/9 had two mutations, whereas no mutations were detected in exon 7.