P53 ONCOPROTEIN ACCUMULATION IN ADENOID CYSTIC CARCINOMA OF PAROTID AND PALATINE SALIVARY-GLANDS

Previous studies have suggested that alterations of the p53 gene are t he most common genetic abnormality in human cancer. The aims of the pr esent study were to evaluate p53 protein (p53P) immunostaining in aden oid cystic carcinoma (ACC) of the salivary gland and to correlate the expression with patient survival. A total of 27 cases of ACC in the pa rotid gland (n = 12) and the minor palatine glands (n = 15) were studi ed, with ten cases each of normal parotid and palatine glands as non-n eoplastic controls. Staining was performed with mouse monoclonal antib ody DO-7 against p53 (Dako, USA) using the ABC method. Stained nuclei irrespective of intensity or frequency were considered as positive. Th e frequency of positive nuclei was evaluated as the p53P index (p53PI) , the percentage of the total nuclei in the reference epithelium. Clin ical survival data were available for patients for periods up to 156 m onths. Our data showed that no normal tissues showed immunoreactivity with p53P in their nuclei. Thirteen of 15 (87%) cases of palatal and t wo of 12 (17%) cases of parotid neoplasms stained with p53P and the p5 3PI ranged from 0.01 to 10%. The number of p53P positive tumors was si gnificantly higher in palatal than in parotid neoplasms, suggesting th at palatal ACCs may be more aggressive in comparison with parotid ACCs . Our data also showed that the number of p53P positive tumors was sig nificantly increased in patients who died of tumors than in patients w ith no evidence of disease at the end of the follow-up period between 60 to 156 months. These results suggest that p53P may be involved in t he development of salivary gland ACCs and that p53P analysis may be a useful indicator of poor prognosis.