p53 mutations in oropharyngeal carcinomas: a comparison of solitary and multiple primary tumours and lymph node metastases.

Despite the steadily increasing number of patients suffering from squamous cell carcinomas of the oropharyngeal region, little is known about the molecular steps involved in the induction of these neoplasms. The aim of this study was to determine the incidence and type of p53 mutations in oropharyngeal squamous cell carcinomas. Five of 38 patients had lymph node metastases, three patients had multiple primary carcinomas and two patients presented with multiple primary tumours and lymph node metastases. Exons 5 through 8 of the p53 gene were screened by single-strand conformation polymorphism analysis followed by direct DNA sequencing. A total of 16 tumours (42%) contained point mutations scattered throughout exons 5 to 8. Most mutations (56%) were transitions, predominantly G-->A. G-->T mutations prevailed among the transversions that have also been found in smoking-related lung cancer. One carcinoma of the soft palate showed a mutation which was retained in a lymph node metastasis. The status of p53 differed in primary carcinomas of patients with multiple tumours indicating an independent generation of these neoplasms. The frequent occurrence of p53 mutations in oropharyngeal carcinomas supports the view that this gene plays a role in initiation or progression of the malignant phenotype.