Abstract No. 143 Functional, Imaging, and Oncological Outcomes in 42 Patients Treated with Lesion-Targeted MRI-Guided Transurethral Ultrasound Ablation (TULSA) for Prostate Cancer Lesions at the Extreme Apex

MRI-guided transurethral ultrasound ablation of the prostate (TULSA) is an emerging modality for treating prostate cancer while reducing the risks of erectile dysfunction and urinary incontinence associated with conventional treatments. The protocol for the pivotal study of TULSA mandated sparing 3 mm apical tissue. We report functional, imaging, and oncologic outcomes in patients with extreme apical lesions treated in the real-world setting. A retrospective subgroup of patients with apical lesions abutting or involving the external sphincter was selected from the overall cohort of men who received TULSA treatment for PCa at our clinic and who have ≥6 month follow-up. Treatment targeted a volume defined by patient preference and disease factors, using intraoperative DWI and ADC maps and T2w imaging. For lesions abutting the external sphincter, a reduced treatment margin of 5 mm around the visible lesion including ≤50% of the external sphincter was applied. Patients were followed daily for 2 weeks, PSA 3-monthly, and MRI, IPSS, IIEF at 6-9 months. Local mpMRI recurrence was assessed using PI-RR. From the overall cohort of 138, 42 men received treatment of apical lesions (37 primary PCa, 5 salvage). Median (IQR) age and follow-up duration were 63 (IQR 59-68) years and 9 (6-16) months. The proportions of men with primary GG 1-5 PCa were 7%, 54%, 20%, 12%, and 7% (all MRI-visible). Median (IQR) target volume was 29cc (22-34, range 10-70), with 99% (98-99%) of the target volume achieving lethal thermal dose ≥240CEM43. PSA decreased from median 6.7 (IQR 4.7-9.7) to 0.9 (0.3-2.0) ng/mL. Of the 28 patients with follow-up MRI, 93% had no evidence of disease; 8,18,0,2,0 had PI-RR scores 1-5. Repeat TULSA was given to both men with PI-RR=4, which led to low likelihood of recurrence (PI-RR=2) and PSA (0.2 ng/mL, 1.0 ng/mL) at 6 mo follow-up. Two men incurred urine leakage resolving by 3 months; all are pad-free. 82% maintained baseline erection firmness sufficient for penetration (IIEF Q2≥2); urinary symptoms (IPSS) were stable. Grade 1-2 adverse events (LUTS, mild hematuria, bladder spasms, and hydrocele) in 10 patients resolved within 4 weeks with oral medication. Two men had Grade 3 events requiring endoscopic intervention (1 retention, 1 retention and bladder neck contracture). No grade ≥4 events and no rectal injuries occurred. This retrospective analysis demonstrates promising safety and efficacy of TULSA in patients with extreme apical lesions. Preservation of urinary continence was favorable even when ablating near the external sphincter.