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INTRODUCTION: Characterization of the index lesion of prostate cancer (PCa) has facilitated the development of focal therapy to reduce complications caused by radical treatments. In the present study, we sought to identify factors associated with the oncological results of focal therapy for PCa. METHODS: Between April 2017 and February 2020, 123 PCa patients received focal therapy performed with high-intensity focused ultrasound (HIFU). The patients presented unilateral localized disease, PSA < 20 ng/dl, clinical stage T1-T2, ISUP grade 1-3, and more than 10 years of life expectancy. Five certified surgeons with different levels of experience performed the procedures and were divided into groups #1 and #2 (>30 HIFUs performed) and #3 (10-15 HIFUs performed each). All patients were prospectively followed and underwent surveillance biopsy 1 year post-treatment. The primary endpoint was radical treatment, and secondary endpoints included focal therapy failure and in-field recurrence. Univariate and multivariate logistic regression were used to detect associations between clinical and procedure variables and the endpoints. RESULTS: The median follow-up was 54.3 months, with a mean age of 64.4 years. The mean PSA was 6.6 ng/dl; 59.3% of patients had intermediate-risk disease, and the remaining had low-risk. During follow-up, 29 (23.6%) patients required radical treatment (external beam radiation therapy), 37 (30.1%) experienced treatment failure, and 26 (21.1%) had an in-field recurrence with an ISUP grade of ≥2. Radical treatment in the follow-up was associated with patients treated by surgeons in group #3 and with elevated post-HIFU PSA concentrations. Baseline PSA concentrations, group #3 surgeons, and post-HIFU PSA concentrations were associated with treatment failure. In-field positive biopsies were associated with baseline and post-HIFU PSA concentrations. Furthermore, patients treated by surgeons in group #3 were independently associated with radical treatment and focal therapy failure. CONCLUSION: Focal therapy with HIFU has acceptable oncological outcomes in the medium term, and the surgeon's experience and technique are independently associated with the need for subsequent radical treatment and focal therapy failure.

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PURPOSE: To review the current evidence regarding protocols and outcomes of image-guided focal therapy (FT) for prostate cancer (PCa). METHODS: A literature search of the latest published studies assessing primary FT for PCa was carried out in Medline and Cochrane library databases followed by a critical review. FT modalities, follow-up strategies, and oncological and toxicity outcomes were summarized and discussed in this review. RESULTS: Twenty-four studies with six different sources of energy met the inclusion criteria. A heterogeneity of patient selection, energy sources, treatment templates, and definitions of failure was found among the studies. While a third of patients may be found to have additional cancer burden over 3-5 years following FT, most patients will remain free of a radical procedure. The vast majority of patients maintain urinary continence and good erectile function after FT. Acute urinary retention is the most common complication, whilst severe complications remain rare. CONCLUSION: An increasing number of prospective studies with longer follow-up have been recently published. Acceptable cancer control and low treatment toxicity after FT have been consistently reported. Follow-up imaging and routine biopsy must be encouraged post-FT. While there is no reliable PSA threshold to predict failure after FT, reporting post-FT positive biopsies and retreatment rates appear to be standard when assessing treatment efficacy.

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PURPOSE: To evaluate whether patients with prostate cancer have worse functional urinary recovery with focal brachytherapy (FBT) at the base versus the apex of the prostate. METHODS AND MATERIALS: The functional outcomes of patients treated with FBT at the base of the prostate were compared with those of patients treated with FBT at the apex. Urinary symptoms, continence, and erectile dysfunction were measured using the International Prostate Symptom Score (IPSS), International Continence Score (ICS), and International Index of Erectile Function (IIEF-5) questionnaires, respectively, at baseline and at 6, 12, and 24 months after treatment. RESULTS: Twenty-eight and 13 patients were treated with FBT at the apex and the base, respectively, of the prostate. A significant difference between groups was found in the IPSS score at 6 months (mean IPSS: apex 6.4 ± 4.7, base 10.6 ± 5.7; p = 0.02), but not at baseline or at 12 and 24 months after treatment. On multivariate analysis, only FBT at the base of the prostate remained an independent predictor of worsening urinary symptoms (odds ratio, 5.8; p = 0.04). CONCLUSIONS: At 6 months after FBT, significantly less urinary toxicity was found in patients who underwent FBT at the apex versus the base of the prostate. Continence and sexual side effects were minimal in all patients.

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Targeted focal therapy strategies for treating single-lobe prostate cancer are under investigation. In this planning study, we investigate the feasibility of treating a portion of the prostate to full-dose external beam radiation with reduced dose to the opposite lobe, compared with full-dose radiation delivered to the entire gland using hypofractionated radiation. For 10 consecutive patients with low- to intermediate-risk prostate cancer, 2 hypofractionated, single-arc volumetric-modulated arc therapy (VMAT) plans were designed. The first plan (standard hypofractionation regimen [STD]) included the entire prostate gland, treated to 70 Gy delivered in 28 fractions. The second dose painting plan (DP) encompassed the involved lobe treated to 70 Gy delivered in 28 fractions, whereas the opposing, uninvolved lobe received 50.4 Gy in 28 fractions. Mean dose to the opposing neurovascular bundle (NVB) was considerably lower for DP vs STD, with a mean dose of 53.9 vs 72.3 Gy (p < 0.001). Mean penile bulb dose was 18.6 Gy for DP vs 19.2 Gy for STD (p = 0.880). Mean rectal dose was 21.0 Gy for DP vs 22.8 Gy for STD (p = 0.356). Rectum V70 (the volume receiving ≥70 Gy) was 2.01% for DP vs 2.74% for STD (p = 0.328). Bladder V70 was 1.69% for DP vs 2.78% for STD (p = 0.232). Planning target volume (PTV) maximum dose points were 76.5 and 76.3 Gy for DP and STD, respectively (p = 0.760). This study demonstrates the feasibility of using VMAT for partial-lobe prostate radiation in patients with prostate cancer involving 1 lobe. Partial-lobe prostate plans appeared to spare adjacent critical structures including the opposite NVB.

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Prostate cancer is a common malignancy among men, and the current screening, imaging and sampling approaches aim to detect early-stage, organ-confined disease. In such scenario, focal prostate cancer therapy currently relies on the index lesion concept as the dominant lesion that drives the disease natural history. Focal therapy demands the essential imaging and sampling techniques to strategically locate and qualify the disease, but, despite advances in technology, prostate imaging and biopsy have several limitations that need to be overcome if focal therapy is to be developed further. The I Prostate Cancer Focal Treatment International Symposium was convened to foster discussion on this topic that sits at the crossroads of multiple disciplines (Urology, Pathology, Radiology, Radiation Oncology and Medical Oncology) all of which were represented for this comprehensive multidisciplinary review of the current literature.

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