Background: Optimising therapeutic strategies of intermediate-risk non-muscle-invasive bladder cancer (IR-NMIBC) is needed.
Objective: To compare recurrence-free survival (RFS) with adjuvant intravesical mitomycin C (MMC) at normothermia or hyperthermia using the COMBAT bladder recirculation system at 43 °C for 30 and 60 min.
Design, setting, and participants: A prospective open-label, phase 3 randomised controlled trial (HIVEC-1) accrued across 13 centres between 2014 and 2020 in Spain. After complete transurethral resection of the bladder and immediate postoperative MMC instillation, patients with IR-NMIBC were randomised (1:1:1) to four weekly followed by three monthly 40-mg MMC instillations at normothermia (control; n = 106), 43 °C for 30 min (n = 107), or 43 °C for 60 min (n = 106) were investigated. Therapeutic compliance was defined as four or more instillations.
Outcome measurements and statistical analysis: The primary outcome was RFS at 24 mo in the intention-to-treat (ITT) and per-protocol (PP) populations. The secondary outcomes included progression-free survival at 24 mo, safety outcome measures, and changes in health-related quality of life. Log-rank, Fisher, χ2, and analysis of variance tests were used.
Results and limitations: The ITT 24-mo RFS was 77% for control, 82% for 43 °C-30 min, and 80% for 43 °C-60 min (p = 0.6). The PP 24-mo RFS was 77% for control, 83% for 43 °C-30 min, and 80% for 43 °C-60 min (p = 0.59). Six patients progressed to muscle-invasive disease in the ITT population (four in the control, 43 °C-30 min, and 43 °C-60 min groups each) and four in the PP population (all controls). Serious adverse events occurred in 26 patients (8.1%), and we were unable to demonstrate a difference between groups (p = 0.5). Adverse events, mainly dysuria and spasms, occurred in 124 patients (33% in control, 35% in 43 °C-30 min, and 48% in 43 °C-60 min; p = 0.05). The total International Prostate Symptom Score worsened by 1.2 ± 7.3 points, similarly across groups (p = 0.29). The Functional Assessment of Cancer Therapy-Bladder domains and indexes showed no significant change.
Conclusions: Four-month adjuvant hyperthermic MMC using the COMBAT system for 30 and 60 min in IR-NMIBC is well tolerated, but we did not find it to be superior to normothermic MMC at 24 mo.
Patient summary: We were unable to demonstrate the effectiveness of hyperthermia using the COMBAT system in intermediate-risk non-muscle-invasive bladder cancer. Further evaluation of long-term recurrence and progression, and maintenance regimens appears mandatory.
Keywords: Bladder neoplasia; Bladder recirculation system; European Association of Urology intermediate risk; Hyperthermic intravesical chemotherapy; Mitomycin C.
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