Expression of pS2 protein and its relation with the Ki-67 proliferative indices and tumor recurrence in superficial bladder carcinomas.

Objective: To investigate the expression and possible role of pS2 protein as a predictor of tumor recurrence in superficial transitional cell carcinoma of the bladder and to determine its relation with tumor stage, grade, size, number, recurrence and proliferative activity.

Methods: Paraffin sections of transurethral resection material from 80 patients with superficial transitional cell bladder carcinoma were stained with pS2 and Ki-67 antibodies using the standard streptavidin biotin immunoperoxidase method. Cytoplasmic pS2 staining was scored on a scale of 1-3 and the Ki-67-labelling index was determined as a percentage of positively staining tumor cells.

Results: An inverse relationship was found between pS2 expression and Ki-67 index (p<0.001). pS2 expression showed no relation with any clinicopathological prognostic parameters as well as the recurrence rate. The recurrence rate was only associated with increased tumor number (p = 0.05), while the time to first recurrence was significantly related to tumor size, proliferative activity and tumor grade (p = 0.04, p<0.001, and p = 0.03, respectively). On the other hand, higher tumor grade was correlated with increased tumor number, Ki-67 index and tumor stage (p = 0.016, p = 0.006, and p<0.001, respectively).

Conclusion: pS2 expression is associated with a low proliferative potential of superficial transitional cell carcinoma of the bladder, while it does not seem to be related to the recurrence rate of the tumor and other prognostic factors. Tumor size and proliferative activity may aid in the estimation of the time to the first recurrence.