Erectile dysfunction (ED) is a common side effect of any prostate cancer treatment and the role of vessel-sparing low dose rate brachytherapy (LDR-BT) technique has not been previously described.
PRIAPUS (NCT04718987) is a prospective, single-arm clinical trial evaluating feasibility of a novel LDR BT technique designed to spare the prostatic neurovascular bundles (NVB) contralateral to the index lesion. Intermediate-risk prostate cancer patients with clinically significant disease contained to one lobe of the prostate were enrolled. Primary objective was for 70% of patients to achieve acceptable dose to CTV while sufficiently sparing ED-related structures. Dosimetry was evaluated on a 1-month postimplant CT-scan.
Fifteen patients have been consented with 14 patients treated on trial. In the 1-month postprocedure scan, the mean CTV D90% was 152 Gy (SD ± 10.7 Gy). All patients but two had a CTV D90% >140 Gy. The mean urethra D30% was 129% (SD ± 9%). The mean contralateral NVB D50% was 60.8 Gy (SD ± 12.1 Gy), with 11 of 14 implants failing to meet the prespecified goal. The ipsilateral NVB which was not spared received a mean D50% of 128 Gy (SD ± 32 Gy). The mean penile bulb D10% was 31 Gy (SD ± 13 Gy). Only 2 patients had a postimplant dosimetry that met all prespecified criteria.
A novel LDR BT technique is capable of drastically reduce dose to the cNVB, although this reduction did not meet the stringent dose constraints specified in this trial.
Brachytherapy. 2025 Sep 19 [Epub ahead of print]
Lucas C Mendez, Douglas A Hoover, Matt Mulligan, Rohann J M Correa, Vikram Velker, Joelle Helou, Samih Mohamed, Aneesh Dhar, Maria Thereza Starling, Aaron Fenster, Gary Brahm, Glenn Bauman, David D'Souza, Jason Vickress
Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, Canada. Electronic address: ., Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, Canada., Robarts Research Institute, Western University, London, Ontario, Canada., Department of Radiology, London Health Sciences Centre, London, Ontario, Canada.