External validation and applicability of the EORTC risk tables for non-muscle-invasive bladder cancer

To perform an external validation of the EORTC risk tables and to evaluate their applicability in the patients of our institution by comparing the actual risk of recurrence and progression in our series to those obtained through the application of the EORTC tables. Retrospective study, based on a prospective cohort of 417 patients in follow-up with primary TaT1 bladder tumors, operated on in our center between 1998 and 2008 and collected in our database. Risk scores were assigned depending on the tumor characteristics to divide our series into four risk groups according to these ratings. An analysis of survival was carried out to calculate the probability of recurrence by the method of Kaplan-Meier. A total of 417 patients with a median follow-up of 59 months were studied. The overall recurrence and progression rates of our series were 25.95% (21.97-30.49) and 4.86% (3.16-7.43) at 1 year and 53.46% (48.06-59.05) and 8.43% (5.95-11.86) at 5 years, respectively. When we compare our rates of recurrence and progression by groups with the corresponding values from Sylvester's publication, an overlapping of the confidence intervals between both populations is detected. In terms of the applicability of the EORTC risk tables in our patients' population, we conclude that these tables predict accurately the clinical course of patients with NMIBC. Due to the sample size of our study, we can only validate the recurrence model of the EORTC tables.