Role of Systematic Control Biopsies following Partial Gland Ablation with High-Intensity Focused Ultrasound for Clinically Significant Prostate Cancer

Purpose: Partial gland ablation (PGA) using high-intensity focused ultrasound (HIFU) is currently under investigation for clinically significant prostate cancer (Cs-PCa). Our primary objective was to assess the role of systematic control biopsies following HIFU-PGA in a cohort of Cs-PCa patients. Materials and Methods: We studied a single-center retrospective cohort of 77 men treated with HIFU-PGA between October 2015 and December 2019. Patients with unilateral Cs-PCa, defined as Gleason grade group (GGG) >= 2, with visible lesion on multiparametric magnetic resonance imaging (mpMRI) and prostate specific antigen (PSA) <= 15 ng/ml were included. All patients underwent mpMRI with systematic and targeted biopsies before and after HIFU-PGA. The primary outcome was the rate of Cs-PCa at control biopsy within 1 year of treatment. Logistic regression was performed to identify predictive factors of our primary outcome. Results: Median age was 67 years (IQR 61-71), median PSA was 7 ng/ml (IQR 5.5-8.9). Pre-treatment biopsies revealed 48 (62.3%) GGG2 lesions, 24 (31.2%) GGG3 and 5 (6.5%) GGG4 lesions. Cs-PCa was found in 24 (31.2%) patients at systematic control biopsy post-HIFU; Cs-PCa was in the treated lobe for 18 (27%) patients. No variables were identified as significant predictors of Cs-PCa at control biopsy, including PSA kinetics and control mpMRI. Median followup time was 17 months (95% CI 15-21). Median time to any retreatment was 32 months (95% CI 23-42). Conclusions: Systematic control biopsy within a year after PGA for Cs-PCa can identify the presence of residual Cs-PCa in up to a third of patients. From our early experience, control biopsy should be systematically offered patients regardless of PSA kinetics or control mpMRI results.