THE PROGNOSTIC-SIGNIFICANCE OF P53 EXPRESSION FOR SURVIVAL AND LOCAL-CONTROL IN RECTAL-CARCINOMA TREATED WITH SURGERY AND POSTOPERATIVE RADIOTHERAPY

Purpose: To investigate whether p53 immunoreactivity is a prognostic f actor for survival and pelvic control in rectal carcinoma treated with surgery and postoperative radiotherapy. Methods and Materials: From 1 981 through 1989, 146 patients with rectal carcinoma received postoper ative radiotherapy and were followed for at least 5 years or until dea th. The specimens of 123 of these 146 patients could be retrieved and examined immunohistochemically for p53 expression. The prognostic valu e for survival and pelvic control of p53 expression and other patient and treatment factors was examined by univariate and multivariate anal yses. Results: p53 expression has no prognostic significance for overa ll survival in this group of 123 patients. The only prognostic factor for survival in this material is tumor stage (p < 0.01). The actuarial pelvic recurrence rates of p53- and p53+ cases are different in favor of the p53- ones. In the univariate analysis this difference is signi ficant (p = 0.05). However, in the multivariate analysis the influence of p53 expression, additional to stage, becomes nonsignificant (p = 0 .10). This indicates that p53 expression is not a strong independant p rognostic factor for pelvic recurrence. In the multivariate analysis s tage turns out to be the only predictor of pelvic recurrence (p = 0.03 ). When only recurrences inside the radiation field are considered, th ere is no difference between p53+ and p53- cases. Conclusion: Based on this material, we have found no convincing evidence that p53 expressi on is an important predictor of survival or local control in rectal ca ncer treated with surgery and postoperative radiotherapy. We have foun d no evidence that possible differences in radiosensitivity between p5 3+ and p53- tumors have clinical significance for this group of patien ts. (C) 1998 Elsevier Science Inc.