p53 status: an indicator for the effect of preoperative radiotherapy of rectal cancer.

Abstract

Rectal carcinoma is a common malignancy, with a history of high local recurrence rates following surgery. In recent years. preoperative radiotherapy and refined surgical technique have improved local control rates. To investigate the relationship between expression of nuclear p53 protein and the outcome in rectal carcinoma, with and without short-term preoperative radiotherapy. Specimens from 163 patients from the Southeast Swedish Health Care region included in the Swedish rectal cancer trial between 1987-1990. New sections from the paraffin blocks of the preoperative biopsy and the surgical specimen were examined immunohistochemically using a p53 antibody (PAb 1801). Expression of nuclear p53 protein was seen in 41% of the tumours. The p53 negative patients treated with preoperative radiotherapy had a significant reduction of local failure compared with the non-irradiated p53 negative patients (P = 0.0008). In contrast, p53 positive patients showed no benefit from preoperative radiotherapy. The interaction between p53 status and the benefit of radiotherapy was statistically significant (P = 0.018). Expression of nuclear p53 protein in rectal carcinoma seems to be a significant predictive factor for local treatment failure after preoperative radiotherapy. Further investigations are necessary to select patients for preoperative treatment based on analysis of the preoperative biopsies.