p53 expression in leukoplakia and carcinoma of the tongue

There is growing interest in assessing multistep carcinogenesis and predicting its course using different molecular markers. TP53 is a tumor suppressor gene and appears to be one of the molecular targets of tobacco-related carcinogens in oral cancer. The present study evaluated the role of p53 expression in patients with leukoplakia and carcinoma of the tongue. p53 expression was studied by immunohistochemistry. All patients with leukoplakia of the tongue were male tobacco users. Nuclear staining of p53 was observed in 79% of those patients. Fifty percent, 25% and 4% of the patients expressed 1+, 2+ and 3+ nuclear staining, respectively. When leukoplakia patients were graded according to histopathology, 67% had hyperplasia and 33% had dysplasia. Nuclear p53 accumulation was 88% in hyperplasia and 62% in dysplasia. In patients with tongue cancer, nuclear accumulation of p53 was seen in only 19% of the tumors, with a staining intensity of 1+ in 13%, 2+ in 2% and 3+ in 4% of the tumors. The prevalence of nuclear p53 positivity (79%) was significantly higher in patients with leukoplakia than in patients with tongue cancer (19%; chi2 = 34.32, r = -0.45, df = 1, p = 0.0001; odds ratio (OR) = 16.66, 95% CI, 5.25-52.86). Therefore, leukoplakia patients who show p53 expression have a higher risk of developing tongue cancer than those who do not show p53 expression. As the percentage of positivity of nuclear p53 was very low, none of the clinicopathological parameters or disease status showed any significant association with it. The interesting finding is that none of the female cancer patients showed nuclear p53 expression. Therefore, p53 accumulation is believed to be an early event in neoplastic progression of the tongue.