Transperineal Targeted Microwave Ablation (TMA) of localized prostate cancer guided by MRI-Ultrasound fusion and organ-based tracking: a pilot study.

BACKGROUND: To investigate the efficacy of transperineal targeted microwave ablation (TMA) in treating localized prostate cancer (PCa). METHODS: This is a single-centre prospective phase 2 trial recruiting men with low to intermediate-risk localized PCa to undergo transperineal TMA. TMA was performed with MRI-Ultrasound fusion guidance and organ-based tracking. A per-protocol 6-month MRI and biopsy were performed for all patients. The primary outcome was any cancer detected on biopsy of each ablated area. Secondary outcomes included per-patient analysis of positive biopsy, complications, urinary symptom score, erectile function and quality of life (QOL) scores. RESULTS: In the first 15 men, 23 areas were being treated. The median age was 70 years, number of TMA ablations were 5 (range 2-8), and the total ablation time and operating time was 22 (IQR 14-28) and 75 (IQR 65-85) minutes, respectively. PSA level dropped from a median of 7.7 to 2.4 ng/mL. For the primary outcome, 91.3% (21/23) ablated area had no cancer in 6-month biopsy. In per-patient analysis, 33.3% (5/15) had in or out-of-field positive biopsy at 6 months. Among these five cases, four of them were amenable to active surveillance and 1 (6.7%) case with out-of-field ISUP grade group 2 cancer received radiotherapy. The urinary symptoms, uroflowmetry, erectile function, and QOL scores had no significant difference at 6 months. One patient (out of five patients with normal erection) in the cohort complained of significant worsening of erectile function after TMA. Grade 1 complications including hematuria (33.3%), dysuria (6.7%), and perineal discomfort (13.4%) were observed. CONCLUSIONS: In this first pilot study, transperineal TMA guided by MRI-Ultrasound fusion guidance and organ-based tracking was shown to be effective, safe, and easily applicable in men with localized PCa.