p53 immunoexpression in non-malignant oral mucosa adjacent to oral squamous cell carcinoma: potential consequences for clinical management

p53 is a tumour suppressor gene encoding a protein whose function is impair ed in a very large proportion of human cancers, The objectives of this stud y were to determine the natural history of p53 alterations during stages of oral carcinogenesis, by comparing p53 immunoexpression in oral squamous ce ll carcinomas (OSCCs), their non-malignant adjacent mucosa, and respective metastases; and to define the potential practical consequences for clinical management of p53 staining in the non-malignant adjacent mucosa, Forty-two samples of non-malignant mucosa adjacent to OSCCs, the respective carcinom as, and six lymph node metastases derived from six of the OSCCs were invest igated for p53 protein expression by immunohistochemistry. Seven out of 42 (17%) non-malignant mucosal samples immediately adjacent to OSCC showed sup rabasal p53 staining and this was significantly associated with moderate/se vere dysplasia (p = 0.02). In six of these cases (86%), the respective carc inoma showed p53 immunoexpression in more than 50% of the neoplastic cells and in the remaining case, p53 immunoexpression was found in more than 25% of the neoplastic cells, In all p53-negative carcinomas that showed p53 imm unoexpression in the non-malignant adjacent mucosa, p53 staining was never detected above the basal cell layer, Lymph node metastases showed the same patterns of p53 immunoexpression as the carcinomas from which they were der ived, When suprabasal p53 staining is present in non-malignant mucosa immed iately adjacent to OSCCs, this suggests stable p53 alterations which are ma intained upon progression to overt malignancy, The immunostaining in non-ma lignant mucosa of the resection margins of OSCCs might be a valuable predic tor for local recurrences and may therefore have implications for the manag ement of patients who have received surgical treatment for OSCC, Copyright (C) 2000 John Wiley & Sons, Ltd.