Targeted microwave ablation of localised prostate cancer: Initial results of VIOLETTE trial.

Objective: The aim of this study was to assess the precision and safety of targeted microwave ablation (TMA) using organ-based tracking (OBT) fusion, in patients with intermediate risk prostate cancer. Patients and method: We conducted a prospective, multicentric trial. Eligible patients had a prostate-specific antigen (PSA) < 20 ng/mL, a magnetic resonance imaging (MRI)-visible index tumour of Gleason score 3 + 4, with largest axis ≤15 mm and distant of at least 5 mm from the rectum and apex. TMA was performed with microwave needle applicator using OBT fusion, with a transperineal or a transrectal approach. In this interim analysis, we evaluated precision, safety, urinary and sexual outcomes, and PSA density kinetics. Results: At this point, 37 patients were treated in five centres. Median (interquartile range) age is 68 (63-72) years. Baseline median prostate volume and PSA are of 45 (34-57) mL and 8 (6.2-10.8) ng/mL, respectively. Median largest tumour axis on T2W MRI is of 11 mm (10-13). Patients were treated under general anaesthesia or conscious IV sedation in an outpatient setting. Anaesthesia had a median duration of 78 (66-90) min. A median number of 3 (2-4) 12-W ablations of 2 to 5 min were performed per patient. After a median follow-up of 6 (2.4-10) months, we observed 58 adverse events (AE) in 22 patients. These were of Common Terminology Criteria for Adverse Events (CTCAE) grade 1, 2 and 3 in 43 (74%), 13 (22%) and 2 (4%) cases. Six (15%) patients had an acute urinary retention, five of which considered as severe AE because of rehospitalisation. We did not observe any significant difference in International Prostate Symptom Score (IPSS), Male Sexual Health Questionnaire-ejaculatory dysfunction (MSHQ-EjD) and International Index of Erectile Function (IIEF5) from baseline to last follow-up. Median PSA density evolved from 0.2 (0.1-0.3) at baseline to 0.1 (0.07-0.16) at 12 months. Conclusions: These preliminary results suggest that TMA using OBT fusion is precise and safe in patients with intermediate risk localised prostate cancer. Further inclusions and follow-up are needed to assess oncological outcome.