Targeted Microwave Ablation for Prostate Cancer Under Magnetic Resonance Imaging-Ultrasound Fusion and Organ-based Tracking: Final Results from the First Phase 2 Trial (TMA-HK)

Targeted microwave ablation (TMA) is a novel focal therapy modality for prostate cancer (PC). TMA-HK is the first phase 2 trial investigating the efficacy and functional outcomes of transperineal TMA (NCT04113811) in 30 men with low- or intermediate-risk PC. TMA was performed transperineally with magnetic resonance imaging (MRI)-ultrasound fusion guidance and organ-based tracking. All participants underwent prostate MRI at 6 mo after TMA, followed by targeted and 18-core systematic prostate biopsy. The primary outcome was cancer detection on biopsy in each ablated area at 6 mo. Secondary outcomes included per-patient analysis of positive biopsy results, complications, and functional outcomes at 12 mo. A total of 42 areas were treated in 30 patients (seven low-risk and 23 intermediate-risk PC), with no cancer detected in 90.5% (38/42) of the treated areas. Per-patient analysis revealed in-field recurrence in 10.0% (three of 30) of patients, of whom two had grade group 1 and one had grade group 2 disease. At 12 mo, out-of-field biopsies were positive in 40.0% (12/30) of the patients (ten grade group 1, two grade group 2 disease). Only self-limiting grade 1 and 2 complications were reported. Three patients (10.0%) reported de novo failure to achieve penetrative sexual intercourse. The results demonstrate that TMA for PC resulted in effective ablation, with good cancer control up to 12 mo. PATIENT SUMMARY: We performed the first efficacy trial of targeted microwave treatment for prostate cancer in 30 patients with low- or intermediate-risk disease. Our results show that this treatment achieved excellent local control of the cancer up to 12 months, with a low rate of complications. More research in larger patient groups and over longer follow-up is needed to confirm these findings.