A high-intensity focal ultrasound (HIFU) therapy guided by real-time magnetic resonance imaging (MRI)/trans rectal ultrasound (TRUS) fusion with the Focal One device to perform targeted ablation of prostate cancer (PCa) was recently developed. In recent years, screening strategies for prostate cancer (PCa) have led to overdiagnosis of low-/intermediate-grade organ-confined tumors. Patients with intermediate risk of PCa can be eligible for an active treatment, but in a percentage of cases radical prostatectomy or radioteraphy may be classified as "overtreatment" due to their potential side effects. In this scenario non-surgical focal therapies perfectly fit, since they are characterized by limited systemic effects and low chance of damaging the surrounding anatomical structures. HIFU is one of ablative modalities that have been approved for clinical use within prospective registry studies. Our objective was to compare the safety and functional outcomes of total, hemi, and focal ablation with the latest focal HIFU device.

The patients in this prospective study were treated from 11/2018 to 03/2020 with HIFU using the Focal One® device for low to intermediate risk PCa. Prior to treatment, all patients underwent mpMRI and subsequent MRI/TRUS fusion (FB) and standard biopsy (SB). Patients were stratified according to the type of ablation: total, hemi- or focal ablation. Functional data (IPSS, quality of life [QoL], IIEF-5, maximum flow [Qmax], and postvoid residual [PVR] at flowmetry) were assessed preoperatively and at 1, 3, 6, and 12 months after treatment. Patient-reported symptoms were classified into 'obstructive' and 'irritative' and were therefore compared. ANOVA test was used to compare the 3 groups.

A total of 100 patients with a median prostate volume of 46 (IQR 25-75) ml were enrolled in this study. The median lesion volume was 10 (IQR 6-13) mm. Patients underwent total, hemi-, and focal ablation in the numbers of 15, 50, and 35, respectively. No differences were found between them except for operative time (lower in the focal group, p<0.01).

No differences were found between baseline status and postoperative evaluation in terms of obstructive IPSS elements, IIEF-5, QoL, Qmax, and PVR (all with p value >0.05). While a significantly lower incidence of irritative symptoms was found in the focal group than in the others (p<0.05 at 1, 3, 36 months of follow-up).

In our study, a lower rate of irritative symptoms was reported with focal ablation. This suggests patient-specific HIFU tailoring with the real-time MRI/ TRUS guidance of the Focal One® device can minimize treatment side effects.