Adverse event-related discontinuation of maintenance Bacillus Calmette-Guérin therapy and oncological outcomes in non-muscle-invasive bladder cancer.

BACKGROUND: Maintenance Bacillus Calmette-Guérin (BCG) therapy is a key component of treatment for intermediate-risk to high-risk non-muscle-invasive bladder cancer (NMIBC) and an essential backbone for combination immunotherapy. However, its implementation remains limited by concerns regarding adverse events (AEs). We evaluated the association between AE-related discontinuation of maintenance BCG therapy and oncological outcomes. METHODS: We retrospectively investigated 228 patients with NMIBC who had received adequate induction BCG and were subsequently scheduled to receive 1 year of maintenance BCG therapy between 2007 and 2020. Patients were categorized into an AE-related discontinuation group, a discontinuation for other reasons group, and a maintenance completion group. Recurrence-free survival (RFS) was assessed using Kaplan-Meier curves. Confounding and time-dependent bias were addressed by propensity score matching and landmark analyses at 3, 6, and 12 months. RESULTS: Overall, 108 patients discontinued maintenance BCG because of AEs, 38 discontinued for other reasons, and 82 completed therapy (completion rate, 36%). Five-year RFS did not differ significantly between the AE-related discontinuation group and the maintenance completion group (89.4% vs. 83.5%, p = 0.314). No significant difference in RFS was observed after propensity score matching (p = 0.46). Landmark analyses consistently showed that AE-related discontinuation was not associated with an increased risk of recurrence. CONCLUSIONS: Among patients who had received adequate induction BCG and predominantly achieved adequate BCG exposure, AE-related discontinuation of maintenance BCG was not significantly associated with worse oncological outcomes. Concerns regarding tolerability should not necessarily preclude initiation of maintenance BCG.