Predictive value of cell cycle markers p53, MDM2, p21, and Ki-67 in superficial bladder tumor recurrence

The aim of the study was to determine whether the expression of the cell cy cle markers p53, MDM2, p21, and Ki-67 was predictive of superficial bladder cancer recurrence and to compare the relative predictive power for tumor r ecurrence of a cell cycle index based on the number of abnormally expressed cell cycle markers with a clinicopathological index based on primary clini cal tumor characteristics. The expression of p53, MDM2, and p21 proteins an d the value of the Ki-67 index were analyzed for 244 patients. One hundred ninety-four lesions were determined to be superficial papillary tumors (pT( a)), whereas 50 tumors invaded the lamina propria (pT(1)), Tumor grade was noted low (grade 1) in 83 cases and high (grades 2-3) in 161 cases. An avid in-biotin peroxidase method was performed using monoclonal antibodies again st p53, MDM2, p21, and Ki-67 antigens after antigen retrieval treatment of formalin-fixed specimens. The cell cycle marker index was created using the number of abnormally expressed cell cycle markers according to the followi ng cutoff points: p53 (>5%), MDM2 (>20%), p21 (<5%), and Ki-67 (>10%), The clinicopathological index was created using the following adverse tumor cha racteristics: grades G(2)-G(3), stage pT(1), multifocality, and diameter of tumors >3 cm, Cox regression models were used to calculate the relative ri sks and their 95% confidence intervals associated with disease recurrence f or the clinicopathological index and the cell cycle marker index. The chi(2 ) test was performed to describe the correlation between the Ki-67 index an d p53, MDM2, and p21 protein expression. Kaplan-Meier survival curves were generated to demonstrate the disease-free survival according to these two p rognostic indexes, The clinicopathological index was a strong, independent predictor of disease recurrence where tumors with three or four adverse tum or characteristics at initial resection had over four times the risk of rec urrence than tumors with no risk factors (P for trend = 0.0001). A strong c orrelation was observed between the Ki-67 index >10% and both MDM2 and p21 proteins. MDM2 was overexpressed in 106 tumors (43%), and p53 was overexpre ssed in 47 (19%); Ki-67 was >10% in 171 cases (70%), Thirty-nine tumors (16 %) were p21 negative. The risk of recurrence increased slightly with the nu mber of abnormally expressed cell cycle markers, but when the clinicopathol ogical index was taken into account in multivariate analysis, the cell cycl e marker index was not predictive of disease recurrence (P for trend = 0.72 ), The cell cycle markers studied provided no added prognostic information on disease recurrence after initial resection of papillary superficial tumo rs when the clinicopathological parameters were taken into account.