Real-world use of maintenance bacillus Calmette-Guérin therapy in patients with non-muscle-invasive bladder cancer in Japan: ASUKA study.

Objectives: To investigate the real-world clinical use of maintenance bacillus Calmette-Guérin (mBCG) therapy for high-risk non-muscle-invasive bladder cancer (HR-NMIBC) in Japan. Patients and methods: This multicentre, retrospective, observational study included patients who received intravesical mBCG for HR-NMIBC following transurethral resection of bladder tumours between 2000 and 2023, and who were included in the Japan Urological Oncology Group registry database. Assessments included real-world mBCG treatment duration, the completion rate of planned treatment, reasons for treatment discontinuation and mBCG effectiveness. Results: The study included 886 patients (median [interquartile range] age 71.0 [65.0-77.0] years; male, 83.5%). The median (interquartile range) treatment duration was 11 (6-17) months, with 43.8% of patients completing the physician-determined planned treatment duration. The percentage of patients with mBCG treatment duration of 3, 6, 12, 18 and 24 months was 21.6%, 21.8%, 31.3%, 7.6% and 9.2%, respectively. Adverse events were the most common reason for mBCG discontinuation (49.1%). The recurrence-free survival, progression-free survival, overall survival and bladder preservation durations were numerically shorter in patients treated for 3 months. Conclusions: This first comprehensive study of the real-world use of mBCG treatment for HR-NMIBC in Japan found diverse treatment patterns, with approximately 40% of patients receiving mBCG for <1 year, which is shorter than the guideline-recommended treatment duration. The results underscore the need for early and sustained adverse event management, and provide valuable reference data for optimising mBCG therapy in clinical practice.