ESTRO 2024 - Abstract Book

S2520

Clinical - Urology

ESTRO 2024

References:

1) Calais J, Armstrong WR, Kishan AU, Booker KM, Hope TA, Fendler WP, Elashoff D, Nickols NG, Czernin J. Update from PSMA-SRT Trial NCT03582774: A Randomized Phase 3 Imaging Trial of Prostate-specific Membrane Antigen Positron Emission Tomography for Salvage Radiation Therapy for Prostate Cancer Recurrence Powered for Clinical Outcome. Eur Urol Focus. 2021 Mar;7(2):238-240. doi: 10.1016/j.euf.2020.12.009. Epub 2020 Dec 30. PMID: 33386288; PMCID: PMC8057677. 2) Phillips R, Shi WY, Deek M, Radwan N, Lim SJ, Antonarakis ES, Rowe SP, Ross AE, Gorin MA, Deville C, Greco SC, Wang H, Denmeade SR, Paller CJ, Dipasquale S, DeWeese TL, Song DY, Wang H, Carducci MA, Pienta KJ, Pomper MG, Dicker AP, Eisenberger MA, Alizadeh AA, Diehn M, Tran PT. Outcomes of Observation vs Stereotactic Ablative Radiation for Oligometastatic Prostate Cancer: The ORIOLE Phase 2 Randomized Clinical Trial. JAMA Oncol. 2020 May 1;6(5):650-659. doi: 10.1001/jamaoncol.2020.0147. PMID: 32215577; PMCID: PMC7225913.

2416

Digital Poster

The UPRATE trial: feasibility of seminal vesicle PTV-margin reduction with online adaptive SBRT

Victor J. Brand, Maaike T.W. Milder, Femke E. Froklage, Miranda E.M.C. Christianen, Kim C. de Vries, Mischa S. Hoogeman, Luca Incrocci

Erasmus MC Cancer Institute, University Medical Center Rotterdam, Radiotherapy, Rotterdam, Netherlands

Purpose/Objective:

The low α/β ratio for prostate cancer (PCa) suggests a benefit of ultra -hypofractionation (UHF). However, for a subgroup of high-risk PCa patients, for whom the seminal vesicles (SV) need to be included in the target volume, UHF can be challenging. Generating clinically acceptable UHF treatment plans is difficult for these patients as the SV require a rather generous PTV-margin (around 8 mm). The UPRATE trial (clinicaltrials.gov; NCT05361902) aims to prove feasibility of SV PTV-margin reduction in low volume metastatic PCa. For this purpose, an online adaptive workflow combining daily replanning, using an in-room CT scanner on rails, and intra-fraction fiducial tracking, as available on the CyberKnife system using 2D KV imaging, is used. Here the results of the first 12 patients, including the observed acute toxicity rates, are reported.

Material/Methods:

In this single-arm, single-centre, phase 2 trial, men with histologically and radiologically proven low volume metastatic PCa, referred for local treatment according to the STAMPEDE trial [1] were eligible. After intraprostatic fiducial implantation, patients were treated with six weekly fractions of 6 Gy. All fractions were adapted using the online adaptive workflow for the CyberKnife combining online replanning together with intrafraction fiducial tracking. The clinical target volumes included the prostate and base or entire SV, at the discretion of the treating physician, with PTV-margins of 3 mm around the prostate and 5 mm around the SV. The dose was prescribed to the 95% isodose line aiming for a PTV V95 ≥99% and adherence to all OAR constraints.