Oncologic and Functional Outcomes of Partial Gland Ablation with High Intensity Focused Ultrasound for Localized Prostate Cancer

PURPOSE: We assessed the outcomes of high intensity focused ultrasound as primary treatment of localized prostate cancer in a retrospective series. This represents one of the largest published series of patients at intermediate and high risk. MATERIALS AND METHODS: We performed a retrospective multicenter analysis of patients who underwent partial gland ablation between January 2013 and September 2017. Patients with biopsy proven localized disease and limited multifocality based on magnetic resonance imaging who preferred minimally invasive outpatient therapy were treated with the Sonablate® 500 system. Oncologic and functional outcomes were analyzed as well as risk factors for recurrence. RESULTS: A total of 166 procedures were performed in 150 patients. Grade Group 2 or greater was present in 89% of cases. Mean ± SD followup was 24.3 ± 14.4 months. Mean prostate specific antigen decreased 65% from 7.9 ± 6.8 ng/ml to a nadir of 2.7 ± 3.1 ng/ml. Confirmatory biopsies were performed in 87 patients (52%) at high risk for recurrence. Clinically significant cancer (Grade Group 2 or greater) was detected in 37 cases (42%). Patients with a higher number of positive cores, a medial tumor location or higher prostate specific antigen had a higher probability of recurrence. Salvage treatment was done in 37 patients (24.6%), including 16 repeat partial gland ablation procedures. CONCLUSIONS: Partial gland ablation with high intensity focused ultrasound therapy was safe and it had a minimal impact on functional outcomes. Local recurrence and/or failure occurred in 42% of patients at high risk for recurrence. Medially located tumors were associated with a higher failure rate. Serious complications were rare. Whole gland treatment was avoided in 81% of patients.