The value of maintenance therapy in intermediate-risk non-muscle-invasive bladder cancer

To evaluate which subgroups of patients with intermediate-risk non-muscle-invasive bladder cancer (IR-NMIBC) benefit from maintenance therapy based on the International Bladder Cancer Group (IBCG) risk stratification, as the role of a maintenance course in patients with IR-NMIBC is debated.

We relied on a prospectively maintained database of patients with IR-NMIBC who received intravesical chemotherapy or Bacillus Calmette-Guérin (BCG) (2010-2023). Patients were stratified according the IBCG prognostic algorithm (no, one to two, and three or more risk factors). All patients received at least six induction instillations after index transurethral resection of bladder tumour. We used 3-month landmark stacked cumulative incidence and multivariable Cox regression models to assess the benefit from a maintenance course in terms of risk of recurrence and progression according to the IBCG risk groups stratification.

Among 464 patients, 205 (44%) received BCG treatment and 259 (56%) received intravesical chemotherapy. The median (interquartile range) number of maintenance instillations was 9 (5-11). Over a median follow-up of 57 months, 139 (30%) patients had a recurrence. Patients with no IBCG risk factors had a similar risk of 5-year disease recurrence according to treatment duration (7.7% vs 7.3%; hazard ratio [HR] 0.78, 95% confidence interval [CI] 0.49-1.37, for induction only vs induction plus maintenance, respectively), whereas patients with one to two (5-year risk: 16% vs 13%; HR 0.65, 95% CI 0.48-0.82) or three or more IBCG risk factors (5-year risk: 21% vs 17%; HR 0.48, 95% CI 0.25-0.85) were associated with lower hazards of recurrence if treated with an induction plus maintenance course.

The IBCG algorithm effectively stratifies patients with IR-NMIBC by recurrence risk. In this observational cohort, maintenance therapy was associated with lower recurrence rates in patients with one to two or three or more IBCG risk factors, but not in those with no risk factors. These findings suggest that the IBCG stratification may inform risk-adapted treatment decisions in patients with IR-NMIBC.