Feasibility, Safety, and Functional Outcomes of Pelvic Hypothermia Induced Using a Rectal Cooling Device During Robot-Assisted Radical Prostatectomy: A Phase I/II Trial

Introduction: Radical prostatectomy (RP) is one of the standard treatments for localized prostate cancer. However, in terms of functional outcomes, there are aspects that still need improvements. We designed this prospective phase I/II clinical trial to assess the safety, clinical feasibility, and functional outcomes of hypothermic robot-assisted RP (RARP). Material and Methods: Twenty patients with preoperative total 5-item International Index of Erectile Function scores ≥12 points, scheduled for RARP, were enrolled in the study. Pelvic hypothermia was induced using an endorectal cooling device (BelloCool System). The primary outcome was the completion rate of the planned hypothermic RARP. Secondary outcomes included the drop in neurovascular bundle (NVB) temperature, adverse (including device-related) events, continence, and potency recoveries, and postoperative quality of life. Contemporaneous patients (propensity score-matched for baseline characteristics) who satisfied the inclusion criteria were included in the control group. Results: The completion rate of the planned hypothermic surgery was 100%. The nadir NVB temperature was 24.9 [22.4, 28.2]°C, which was 10.2 [7.0, 13.1]°C lower than the nadir core body temperature. There was no device-related adverse event, and bowel function was well preserved for the whole follow-up period. At 12 months postoperatively, potency and continence recovery rates were higher in the hypothermic group than in the control group (40% vs 15%, p = 0.027 and 95% vs 80%, p = 0.167, respectively). The Kaplan-Meier curve showed faster recovery rate of potency in the hypothermic group (hazard ratios = 3.46, log-rank p < 0.01). Conclusions: Hypothermic RARP using the BelloCool™ endorectal cooling system is safe and feasible. A large-population-based randomized controlled trial is needed to confirm the potential for a benefit in continence and potency recovery.