MRI-directed Micro-US-guided Transperineal Focal Laser Ablation for Localized Prostate Cancer: A 1-year Follow-up Study.

Background MRI-guided focal laser ablation (FLA) is a promising treatment in localized prostate cancer (PCa). MRI-guided micro-US FLA shows potential for outpatient use, but its clinical application remains unexplored. Purpose To evaluate the safety, feasibility, and 12-month functional and oncologic outcomes of MRI-guided micro-US transperineal FLA in localized PCa and to assess the accuracy of micro-US in showing lesions depicted at MRI with Prostate Imaging Reporting and Data System (PI-RADS) score of 3 or higher. Materials and Methods This prospective, single-center observational study (July 2020 to June 2023) included participants with localized low- or intermediate-risk PCa and PI-RADS 3 or higher lesions (≤20 mm). Single- or multifiber FLA was performed at 1064 nm, guided by MRI-delineated image fusion. At 12 months, recurrence rates, complications, erectile function scores, and urinary symptom scores were assessed. Mann-Whitney and Wilcoxon tests were used for comparisons. Results Fifty-five male participants (median age, 70 years; IQR, 62-74 years) with 58 lesions that were PI-RADS 3 or higher underwent transperineal FLA, with a 12-month follow-up for 33 participants. The median prostate-specific antigen level was 7.0 ng/mL (IQR, 5.6-9.0 ng/mL), 43 of 58 lesions (74%) had a Gleason score of 3 + 4, and 10 of 58 lesions (17%) had a Gleason score of 3 + 3. Single-fiber and multifiber FLA were used to treat 21 of 58 (36%) and 37 of 58 (64%) tumors, respectively. At micro-US, 53 of 58 (91%) tumors were successfully visualized. Multifiber FLA produced larger ablation volumes than did single-fiber treatment (median, 15 mL [IQR, 8-22 mL] vs 4.5 mL [IQR, 2.8-9.2 mL]; < .001). At 12 months, biopsies in 35 treated tumors showed 17 recurrences (49%), including 13 in-field and four out-of-field recurrences. In-field recurrences occurred in 10 of 18 (56%) single-fiber and three of 17 (18%) multifiber cases. At 12 months, erectile function scores decreased compared with baseline (median International Index of Erectile Function score, 19 [IQR, 12-24] vs 21 [IQR, 15-24]; < .001), whereas urinary function remained stable (median International Prostatic Symptom Score, 2 [IQR, 2-9] vs 6 [IQR, 3-11]; = .72). One rectoprostatic fistula developed and required surgery. Conclusion Multifiber micro-US-guided FLA was safe and feasible, with 18% recurrence at 1-year follow-up. Clinical trial registration no. NCT05163197 © RSNA, 2024