Contemporary outcomes in non-muscle-invasive bladder cancer: a large European multicentre study

Objective To report real-world rates of non-muscle-invasive bladder cancer (NMIBC) recurrence and progression within a European multicentre cohort with detailed information on intravesical instillation courses, as contemporary data on oncological outcomes in NMIBC are limited. Patients and methods A total of 1918 patients with NMIBC treated with transurethral resection of bladder tumour (TURBT) were retrospectively identified from six tertiary-referral European centres (2015-2022). Patients were stratified according to European Association of Urology 2021 criteria into low- (LR), intermediate- (IR), high- (HR) and very high-risk (VHR) categories. Cumulative incidence plots and multivariable competing risks regression models addressing 5-year rates of high-grade (HG) recurrence and progression were fitted. Sensitivity analyses focused on patients receiving intravesical instillations and tested for the effect of adequate course (Bacillus Calmette-Guerin: five or more induction + two or more maintenance instillations; mitomycin C: complete induction + >= 11 maintenance instillations). Results Of all NMIBC patients identified, 467 (24.3%) were LR vs 582 (30.3%) IR vs 739 (38.5%) HR vs 130 (6.8%) VHR. The median (interquartile range) follow-up after TURBT was 26 (12-46) months. The 5-year HG recurrence rates were 7.2% in LR vs 17.3% in IR vs 26.7% in HR vs 30.9% in VHR patients, resulting in a three-, five- and seven-fold higher risk of IR, HR and VHR, respectively, relative to LR (all P < 0.001). The 5-year progression rates were 3.9% in LR vs 5.2% in IR vs 13.6% in HR vs 31.6% in VHR patients, resulting in a six- and nine-fold higher risk for HR and VHR, respectively, relative to LR (all P < 0.001). In all, 1001 (52.2%) patients underwent intravesical instillations. Those receiving adequate instillation course (244/1001 [24.3%]) had lower HG-recurrence (hazard ratio 0.3, P < 0.001) and progression (hazard ratio 0.2, P = 0.001) risk. Conclusions Patients with HR/VHR NMIBC face significantly higher HG recurrence and progression risks. While tailored treatment strategies are needed, adherence to adequate instillation course remains crucial for optimising oncological outcomes.