Correlation and prognostic significance of p53, p21WAF1/CIP1 and Ki-67 expression in patients with superficial bladder tumors treated with bacillus Calmette-Guerin intravesical therapy

Abstract

Purpose: We determine if, before intravesical bacillus-Calmette Guerin (BCG) therapy, p53, p21WAF-1-CIP1 (a critical downstream effector of p53 pathway of cell growth control, inhibiting cyclin dependent kinases) and the cell proliferation marker Ki-67 (MIB-1) could be used as prognostic markers of response to BCG in patients with superficial bladder tumors.

Materials and methods: The study included 47 patients with superficial bladder tumors at high risk for recurrence or progression treated with 6 weekly intravesical BCG instillations. We analyzed p53, p21 and Ki-67 on paraffin embedded samples by immunohistochemistry and the percentage of positive cells was determined in a blinded fashion. Quantitative immunostaining was analyzed in relation to time to recurrence and progression using univariate or multivariate analysis and the Kaplan-Meier method.

Results: During a mean followup of 24.6 months 23 of the 47 patients (48.9%) presented with tumor recurrence and 10 (21.2%) had later progression to invasive disease. A p21 over expression (greater than 10%) was observed in 23 tumors (48.9%) and positively correlated with p53 (p = 0.0097) but not with Ki-67 (p = 0.327). Of the tumors 18 (38.2%) were p53 and p21 negative. Among p21 positive tumors 15 (65.2%) were p53 and p21 positive, suggesting that p21 may also be regulated by p53 independent pathways. However, p53 did not act as a predictor of recurrence or progression. In contrast, using Kaplan-Meier curves p21 over expression (greater than 10%) and Ki-67 at a 25% cutoff were associated with shorter recurrence-free survival (both p = 0.02 log rank test) but they did not predict additional information about risk of progression. However, multivariate analysis failed to demonstrate any independent prognostic value for p21 or Ki-67 in contrast to tumor stage.

Conclusions: Our results indicate that p21WAF-1-CIP1 seems to be regulated by p53 independent pathways in superficial bladder cancer. The present study did not indicate an independent prognostic significance in patients treated with BCG for p53, p21WAF-1-CIP1 or Ki-67 markers. Larger prospective studies are needed to evaluate further the independent value of these biological markers in superficial bladder cancer management.