Lack of molecular markers to predict malignant potential of oral precancer.

Studies on the natural history of oral squamous cell carcinoma suggest a clinically detectable phase which precedes the development of cancer. Among the precancerous states, leukoplakia is the most commonly encountered clinical lesion. Although epithelial dysplasia is the most important predictive factor, non-dysplastic lesions in the oral cavity may transform with time. Early reports describing p53 overexpression in oral leukoplakia has resulted in many authors misinterpreting this result by concluding that p53 is an early marker of oncogenesis. Using sequential biopsies, few reports have critically examined the clinical significance of p53 as a risk marker. These studies suggest that p53 protein stabilization, or indeed the spectrum of mutations of p53, has no major relationship to the biological characteristics and outcome of oral leukoplakia. When used as a single marker, p53 is unsuitable for the prediction of tumour development in high-risk subjects and no other maker has yet emerged as useful. Despite the impact of molecular diagnostics on the diagnosis of tumours, assessing a patient's risk for development of cancer of the oral cavity remains limited to 'H&E' pathology. Copyright 2000 John Wiley & Sons, Ltd.