Efficacy and tolerability of adjuvant hyperthermic intravesical chemotherapy (HIVEC) with mitomycin-c for high-risk non-muscle-invasive bladder cancer: a single-centre Australian experience

Purpose: To evaluate the oncological efficacy and tolerability of adjuvant hyperthermic intravesical chemotherapy (HIVEC) with mitomycin-C (MMC) in high-risk non-muscle-invasive bladder cancer (NMIBC) patients treated at a single Australian tertiary referral centre. Methods: A retrospective analysis was performed on a prospectively maintained database of high-risk NMIBC patients treated with HIVEC using the Combat Bladder Recirculation System. Patients received weekly induction (six cycles) followed by monthly maintenance therapy for up to 10months. Primary outcomes were 12-month recurrence-free survival (RFS) and treatment tolerability. Secondary endpoints were 12-month progression-free survival (PFS) and overall survival (OS). Adverse events (AEs) were graded according to the Common Terminology Criteria for Adverse Events version 5.0. Results: 26 patients were included (median age 79.5 years). 20 patients (76.9%) had previous BCG exposure. Nine (34.6%) had carcinoma-in-situ (CIS) present at referral. Median follow up was 14.7 months. 25 patients completed induction (96.2%) and six(23.1%) completed a full maintenance course. At 12 months, RFS, PFS, and OS were 59.7%, 95.7%, and 100% respectively. Median time to recurrence was 6.7 months. AEs were reported in 80% of patients, though all were grade 1 or 2. Haematuria (65%), urinary tract infection (46%), and urinary frequency (46%) were the most common AEs. Four patients (15%) discontinued therapy for AE intolerance. No grade ≥3 or systemic toxicities occurred. Conclusions: HIVEC with MMC achieved oncological outcomes comparable to international data while maintaining acceptable tolerability. These findings support HIVEC with MMC as a feasible, well-tolerated, bladder-preserving alternative for patients with high-risk, BCG-refractory NMIBC who are unsuitable for radical cystectomy.