Impact of substratification on predicting oncological outcomes in patients with primary high-risk non-muscle-invasive bladder cancer who underwent transurethral resection of bladder tumor

Objectives To validate the substratification of high-risk in the European Association of Urology (EAU) guidelines and to develop the simplified substratification to improve usefulness and predictive accuracy on oncological outcomes in patients with primary high-risk nonmuscle-invasive bladder cancer (NMIBC) who underwent transurethral resection of bladder tumor (TURBT). Materials and methods We retrospectively evaluated 428 patients with primary high-risk NMIBC who underwent TURBT from November 1993 to April 2019. First, the efficacy of the EAU highest-risk on intravesical recurrence-free survival (RFS) and muscle-invasive bladder cancer (MIBC)-free survival was evaluated with univariate analyses. Second, we developed our simplified substratification based on multivariate analysis for intravesical RFS (lower- and higher-risk). We compared predictive accuracy on oncological outcomes using the receiver operating characteristic curve between the EAU and the simplified substratifications. Results Median age and median follow-up periods were 72 years and 51 months, respectively. The EAU highest-risk was not associated with shorter intravesical RFS and MIBC-free survival (P = 0.054 and P = 0.350, respectively). In multivariate analysis, tumor size, grade 3, and chronic kidney disease were significantly associated with shorter intravesical RFS, and we developed the simplified substratification including those 3 factors. Of 428 patients, 89 (21%) were substratified into the simplified higher-risk. The predictive accuracy of the simplified substratification on intravesical recurrence, MIBC and metastasis progression, and cancer-specific mortality was significantly superior to the EAU substratification. Conclusion Our simplified substratification might contribute to improving predictive accuracy on intravesical recurrence, MIBC and metastasis progression, and cancer-specific mortality in patients with primary high-risk NMIBC who underwent TURBT.