BACKGROUND.
The aim of this study was to elucidate the associations among immunostaining for p53, p21, and mdm2; their respective expression within each tumor; and the value of these variables for predicting treatment outcome after cystectomy for patients with locally advanced bladder carcinoma.
METHODS.
The hospital records from all 173 patients treated with cystectomy for locally advanced urothelial bladder carcinoma between 1967 and 1992 were retrospectively reviewed. Three consecutive sections from biopsies taken before any treatment were stained using the standard immunohistochemical technique for p53, p21, and mdm2, respectively. The cutoff limit was 20% or more for positive p53 expression and 10% or more for positive p21 and mdm2 expression.
RESULTS.
Positive immunostaining was observed for p53 in 98 tumors (57%), for p21 in 89 tumors (51%), and for mdm2 in only 16 tumors (9%). The only association found between immunostaining for the three antibodies was that most mdm2positive tumors had positive p21 expression. Tumor mapping of regional immunostaining showed no association between immunostaining for p53 and p21. In a proportional hazards analysis, no association was found between the results of immunostaining for the three antibodies and treatment outcome.
CONCLUSIONS.
Positive or negative expression of p53, p21, or mdm2, or combinations of these, was not associated with cancer specific mortality after cystectomy for bladder carcinoma. There was no association between immunostaining for p21 and p53, whereas positive immunostaining for mdm2 was observed in a minority of the tumors. These results indicate that, in addition to p21, p53, and mdm2, there are other oncoproteins and tumor suppressor proteins along the p53 pathway that are involved in tumor development and progression.