Magnetic Resonance Imaging–Guided Transurethral Ultrasound Ablation of Prostate Tissue in Patients with Localized Prostate Cancer: A Prospective Phase 1 Clinical Trial
Mené sur 30 patients atteints d'un cancer localisé de la prostate à risque faible ou intermédiaire de récidive (âge médian : 69 ans ; durée de suivi : 12 mois), cet essai de phase I évalue la sécurité et la faisabilité d'une ablation transurétrale de l'ensemble de la prostate par ultrasons sous guidage IRM
Background : Magnetic resonance imaging–guided transurethral ultrasound ablation (MRI-TULSA) is a novel minimally invasive technology for ablating prostate tissue, potentially offering good disease control of localized cancer and low morbidity. Objective : To determine the clinical safety and feasibility of MRI-TULSA for whole-gland prostate ablation in a primary treatment setting of localized prostate cancer (PCa). Design, setting, and participants : A single-arm prospective phase 1 study was performed at three tertiary referral centers in Canada, Germany, and the United States. Thirty patients (median age: 69 yr; interquartile range [IQR]: 67–71 yr) with biopsy-proven low-risk (80%) and intermediate-risk (20%) PCa were treated and followed for 12 mo. Intervention : MRI-TULSA treatment was delivered with the therapeutic intent of conservative whole-gland ablation including 3-mm safety margins and 10% residual viable prostate expected around the capsule. Outcome measurements and statistical analysis : Primary end points were safety (adverse events) and feasibility (technical accuracy and precision of conformal thermal ablation). Exploratory outcomes included quality of life, prostate-specific antigen (PSA), and biopsy at 12 mo. Results and limitations : Median treatment time was 36 min (IQR: 26–44) and prostate volume was 44 ml (IQR: 38–48). Spatial control of thermal ablation was ±1.3 mm on MRI thermometry. Common Terminology Criteria for Adverse Events included hematuria (43% grade [G] 1; 6.7% G2), urinary tract infections (33% G2), acute urinary retention (10% G1; 17% G2), and epididymitis (3.3% G3). There were no rectal injuries. Median pretreatment International Prostate Symptom Score 8 (IQR: 5–13) returned to 6 (IQR: 4–10) at 3 mo (mean change: −2; 95% confidence interval [CI], −4 to 1). Median pretreatment International Index of Erectile Function 13 (IQR: 6–28) recovered to 13 (IQR: 5–25) at 12 mo (mean change: −1; 95% CI, −5 to 3). Median PSA decreased 87% at 1 mo and was stable at 0.8 ng/ml (IQR: 0.6–1.1) to 12 mo. Positive biopsies showed 61% reduction in total cancer length, clinically significant disease in 9 of 29 patients (31%; 95% CI, 15–51), and any disease in 16 of 29 patients (55%; 95% CI, 36–74). Conclusions : MRI-TULSA was feasible, safe, and technically precise for whole-gland prostate ablation in patients with localized PCa. Phase 1 data are sufficiently compelling to study MRI-TULSA further in a larger prospective trial with reduced safety margins. Patient summary : We used magnetic resonance imaging–guided transurethral ultrasound to heat and ablate the prostate in men with prostate cancer. We showed that the treatment can be targeted within a narrow range (1 mm) and has a well-tolerated side effect profile. A larger study is under way. Trial registration : NCT01686958, DRKS00005311.