Impact of bladder neck involvement on progression in patients with primary non-muscle invasive bladder cancer: A prospective validation study

PurposeOur previous retrospective study reported that bladder neck involvement (BNI), as well as tumor grade and stage, was a significant risk factor for progression in primary non-muscle invasive bladder cancer (NMIBC). We prospectively validated BNI as a significant predictor for progression using a new cohort of patients with primary NMIBC.Patients and methodsA total of 297 new Japanese patients who underwent transurethral resection and were pathologically diagnosed with Ta or T1 urothelial carcinoma were enrolled in this prospective study. Clinicopathologic data were collected at study entry. Multivariate Cox proportional hazards regression models were performed to identify the independent predictors for progression. A predictive scoring model for progression was developed using the regression coefficients (RCs) from the final multivariate model. The predictive ability of the model was assessed using Harrell's c-index.ResultsWith a median follow-up of 37 months, 16 patients (5.4%) progressed. Progression probability at 1 and 5 years were 1.5% and 8.0%, respectively. Multivariate analysis revealed that histologic grade 3 (hazard ratio [HR] 9.45, P = 0.0004, RC 2.25), pathologic T1 stage (HR 6.91, P = 0.0014, RC 1.93), and BNI (HR 11.75, P = 0.0009, RC 2.46) were all independent predictors of progression. When all 3 variables were scored as 1 point and the patients were divided into 3 groups, progression rates were clearly discriminated (P<0.0001). The c-index was 0.80.ConclusionsThis prospective validation study has shown that BNI is a significant prognostic factor for progression in primary NMIBC. The scoring model including BNI enables the physician to classify patients with primary NMIBC into 3 groups with clearly different progression rates.