External Validation of a Risk Model to Predict Recurrence-Free Survival After Radical Cystectomy in Patients With Pathological Tumor Stage T3N0 Urothelial Carcinoma of the Bladder

PurposePatients with stage pT3N0 urothelial bladder cancer vary in outcome after radical cystectomy. To improve prognosis estimation a model was recently developed that defines 3 risk groups for recurrence-free survival based on pT substaging, lymphovascular invasion and positive surgical margin. We present what is to our knowledge the first external validation of this risk model.Materials and MethodsAnalogous to the risk model derivation cohort our study group comprised 472 patients with stage pT3, pN0, cM0 disease without perioperative chemotherapy and with a median followup of 42 months (IQR 20–75). The primary end point was recurrence-free survival. The effect of variables was determined by univariate and multivariate Cox regression analysis, and predictive accuracy was determined by ROC analysis.ResultsStage pT3aN0 and pT3bN0 cases showed significantly different recurrence-free survival after 5 years (51% vs 29%, p <0.001). In the multivariate Cox model pT3 substage (HR 1.86, p <0.001), lymphovascular invasion (HR 1.48, p = 0.002), positive surgical margins (HR 1.90, p = 0.030) and patient age with a dichotomy at 70 years (HR 1.51, p = 0.001) had an independent effect on recurrence-free survival. In the low (221 patients or 47%), intermediate (184 or 39%) and high (67 or 14%) risk groups the 5-year recurrence-free survival rate was 55%, 45% and 13%, respectively (p <0.001). The concordance index of the risk model to predict recurrence-free survival was 0.64 (95% CI 0.59–0.69).ConclusionsThis user friendly risk model can be recommended to estimate prognosis in patients with stage pT3N0 after radical cystectomy. Patients at high risk showed clearly compromised recurrence-free survival and should be included in adjuvant therapy studies.