Background and objective: The current European Association of Urology (EAU) guidelines on non-muscle-invasive bladder cancer (NMIBC) categorize patients into four risk groups. In 2024, a specific follow-up schedule was introduced for intermediate-risk (IR) disease. However, recommendations are based on expert opinion and restricted to patients with IR-NMIBC who have primary low-grade or high-grade/grade 2 disease. Our aim was to identify a subgroup of patients with IR-NMIBC who may require more stringent follow-up. Methods: We conducted a retrospective analysis of 2086 patients with IR-NMIBC classified according to the World Health Organization 1973 grading scheme. Multivariable Cox-regression models were fitted to identify predictors of recurrence, which were then used to dichotomize groups with low risk of recurrence (IR-Low) versus high risk of recurrence (IR-High). Kaplan-Meier curves were plotted to estimate recurrence-free survival (RFS) and progression-free survival (PFS). Smoothed hazard estimates of first recurrence were plotted by risk group. Key findings and limitations: Multifocality and tumor size ≥3 cm were significantly associated with higher risk of first recurrence and were used to define the IR-High and IR-Low (unifocal, size <3 cm; n = 1087) groups. The 3-yr RFS rate was significantly worse for the IR-High group (51%, 95% confidence interval [CI] 48-54%) than for IR-Low (68%, 95% CI 65-71%). The risk of progression was low (5-yr PFS rate 96%) with no significant difference between the IR-High and IR-Low groups. Conclusions and clinical implications: During IR-NMIBC follow-up for recurrence, tumor size and focality should be considered rather than grade. If the primary objective is to ensure prompt detection of recurrence, follow-up schedules should be tailored according to the risk of recurrence, with more stringent protocols for patients with IR-NMIBC at higher risk of recurrence.
