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

Background: Rectal carcinoma is a common malignancy, with a history of high local recurrence rates following surgery. In recent years, preoperative ra diotherapy and refined surgical technique have improved local control rates . Aim: To investigate the relationship between expression of nuclear p53 prot ein and the outcome in rectal carcinoma, with and without short-term preope rative radiotherapy. Material: Specimens from 163 patients from the Southeast Swedish Health Car e region included in the Swedish rectal cancer trial between 1987-1990. Method, New sections from the paraffin blocks of the preoperative biopsy an d the surgical specimen were examined immunohistochemically using a p53 ant ibody (PAb 1801). Result: Expression of nuclear p53 protein was seen in 41% of the rumours. T he p53 negative patients treated with preoperative radiotherapy had a signi ficant reduction of local failure compared with the non-irradiated p53 nega tive patients (P = 0.0008). In contrast, p53 positive patients showed no be nefit from preoperative radiotherapy. The interaction between p53 status an d the benefit of radiotherapy was statistically significant (P = 0.018). Conclusion: Expression of nuclear p53 protein in rectal carcinoma seems to be a significant predictive factor for local treatment failure after preope rative radiotherapy. Further investigations are necessary to select patient s for preoperative treatment based on analysis of the preoperative biopsies . (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.