Value of p53 expression in oral cancer and adjacent normal mucosa in relation to the occurrence of multiple primary carcinomas.

Paraffin embedded, formalin fixed tissue sections from patients suffering from a primary oral squamous cell carcinoma were immunohistochemically investigated for the presence of p53 expression using the Bp53-11 antibody. The aim of this study was to determine the predictive value of p53 expression as a biomarker for the development of a second primary tumour (SPT) in the respiratory and upper digestive tract. In a nested case control study, neoplastic and normal tissue sections of 44 patients who had a previous history of cancer were used. 15 of the 44 had developed a SPT, while the other 29 were minimally 7 years free of disease. Additionally, nine SPTs were included in this study to establish whether concordance exists in tumours that develop in the same field. 10 of the 29 patients (34%) free of tumour during follow-up had p53 positive tumours. 8 of 15 patients (53%) who developed a SPT had a p53 positive primary tumour. This difference is not statistically different (chi 2-test). Forty percent of the total group of primary oral cavity tumours showed p53 positivity. When comparing the first and the second tumours, discordance in p53 expression between the first and second tumours was seen in 4 out of 9 cases. None of the cases showed p53 positivity in adjacent normal mucosa. In conclusion, p53 immunoreactivity in neoplasia, dysplasia and normal tissue does not predict the development of a SPT. In addition, multiple primary tumours do not have identical p53 expression.