International Bladder Cancer Group Intermediate-risk Nonmuscle-invasive Bladder Cancer Scoring System Predicts Outcomes of Patients on Active Surveillance

Purpose: We sought to determine if the International Bladder Cancer Group IR-NMIBC (Intermediate-risk Nonmuscle-invasive Bladder Cancer) scoring system can predict the requirement of delayed transurethral resection of bladder tumor in low-grade nonmuscle-invasive bladder cancer managed by active surveillance. Materials and Methods: We prospectively studied recurrent low-grade Ta/T1 nonmuscle-invasive bladder cancer patients managed with active surveillance with the following characteristics: low-grade papillary nonmuscle-invasive bladder cancer, ≤5 apparent low-grade nonmuscle-invasive bladder tumors, tumor diameter ≤1 cm, absence of gross hematuria, and negative urinary cytology. Subsequent transurethral resection of bladder tumor was offered to patients who no longer met the inclusion criteria or patient choice. The ability of the International Bladder Cancer Group IR-NMIBC scoring system to predict receipt of subsequent transurethral resection of bladder tumor was determined. Multivariable Cox proportional hazards analysis was used to determine factors associated with subsequent transurethral resection of bladder tumor. Results: A total of 163 patients with low-grade Ta/T1 nonmuscle-invasive bladder cancer were included for analysis. After a median follow-up of 33 months (IQR: 21-46), transurethral resection of bladder tumor was performed on 109 patients. At landmark time point of 24 months, patients with 0 risk factors were over 2-fold more likely to continue active surveillance compared to patients with ≥3 risk factors (59% vs 24%). Multivariable Cox regression suggested that the International Bladder Cancer Group IR-NMIBC scoring system was associated with subsequent transurethral resection of bladder tumor (1-2 risk factors [HR: 1.66, 95% CI: 0.96-2.90, P [ .072], ≥3 risk factors [HR: 3.21, 95% CI: 1.70-6.09, P < .001]) after adjusting for age, T stage, and sex. Conclusions: The International Bladder Cancer Group IR-NMIBC scoring system can predict the risk of subsequent transurethral resection of bladder tumor in patients with low-grade nonmuscle-invasive bladder cancer on active surveillance.