Comparison of Long-Term Oncological Outcomes of Intravesical Bacillus Calmette–Guérin Versus Gemcitabine in Treatment-Naïve Non-Muscle-Invasive Bladder Cancer with Intermediate and High Risk: A Multicenter Retrospective Analysis

Background/Objectives: Although intravesical Bacillus Calmette–Guérin (BCG) is an established adjuvant therapy for non-muscle-invasive bladder cancer (NMIBC), chronic global shortages and adverse events (AEs) can occur. Thus, intravesical gemcitabine has been used as an alternative. We compared the long-term oncological outcomes and safety profiles of BCG and gemcitabine in treatment-naïve patients with intermediate- and high-risk NMIBC. Methods: Patients with intermediate- and high-risk NMIBC (n = 477) received adjuvant intravesical induction and maintenance therapy with intravesical BCG (n = 361) or gemcitabine (n = 116) and their data were collected retrospectively. Results: Compared with the gemcitabine group, the BCG group had significantly higher proportions of patients with T1 stage, high-grade tumors, high-risk tumors, and longer median follow-up duration. Over a median 36-month observation period, the BCG group exhibited significantly better recurrence-free survival (RFS) and high-grade RFS (HG-RFS) than the gemcitabine group. In the propensity score–matched high-risk population, BCG also outperformed gemcitabine in RFS and HG-RFS. BCG therapy was identified as a potent protective predictor, reducing the risk of recurrence and high-grade recurrence by 65% and 66%, respectively, in the total cohort, and by 69% and 71%, respectively, in the propensity score-matched high-risk subgroup. No significant differences were observed in the frequency of grade ≥3 AEs between BCG and gemcitabine. Conclusions: Intravesical BCG is strongly associated with superior oncological outcomes over gemcitabine in intermediate- and high-risk NMIBC. The results of this study offer pivotal practice-based insights to guide clinical strategies for managing NMIBC.