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)

Abstract

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.