Focal high‐intensity focused ultrasound therapy for localized prostate cancer: An interim analysis of the multinational FASST study

Abstract Background High‐intensity focused ultrasound (HIFU) emerged as a novel approach for the treatment of localized prostate cancer (PCa). However, prospective studies on HIFU‐related outcomes and predictors of treatment failure (TF) remain scarce. Materials and Methods We conducted a multinational prospective cohort study among patients undergoing HIFU therapy for localized, low‐ to intermediate‐risk PCa. Follow‐up data on serial prostate specific antigen (PSA), multi‐parametric magnetic resonance imaging (mpMRI), targeted/systematic biopsies, adverse events and functional outcomes were collected. The primary endpoint was TF, defined as histologically confirmed PCa requiring whole‐gland salvage treatment. Uni‐ and multi‐variable adjusted hazard ratios (HRs) were calculated using Cox proportional hazard regression models. Results At baseline, mean (standard deviation) age was 64.14 (7.19) years, with the majority of patients showing T‐stage 1 (73.9%) and International Society of Urological Pathology grading system Grade 2 (58.8%). PSA nadir (median, 1.70 ng/mL) was reached after 6 months. Of all patients recruited, 16% had clinically significant PCa, as confirmed by biopsy, of which 13.4% had TF. Notably, T‐stage and number of positive cores at initial biopsy were independent predictors of TF during follow‐up (HR [95% CI] 1.27 [1.02–1.59] and 5.02 [1.80–14.03], respectively). Adverse events were minimal (17% and 8% early and late adverse events, respectively), with stable or improved functional outcomes in the majority of patients. Conclusions This interim analysis of a multinational study on HIFU therapy for the management of low‐to‐intermediate‐risk PCa reveals good functional outcomes, minimal adverse events and low incidence of TF over the short‐term. Data on long‐term outcomes, specifically as it relates to oncological outcomes, are awaited eagerly.