ESTRO 2025 - Abstract Book

S2129

Clinical - Urology

ESTRO 2025

4381

Digital Poster Safety of PSMA-PET- and MRI-based Focal Dose Escalated Radiotherapy for Prostate Cancer: Primary Endpoint Analysis of the Phase II HypoFocal Trial Simon KB Spohn 1,2 , Constantinos Zamboglou 1,3 , Sophia L Bürkle 1,2 , Martin Freitag 4 , Joachim Brumberg 4 , Hannes Engel 5 , Mark Gainey 6,2 , Marius Kamps 7 , Paolina Toncheva 1,2 , Tanja Sprave 1,2 , Simon Kirste 1,2 , August Sigle 7 , Cordula Jilg 7 , Christian Gratzke 7 , Sonja Adebahr 1,2 , Michael Mix 4 , Fabian Bamberg 5 , Sebastian Zschaeck 8 , Pirus Ghadjar 8 , Dimos Baltas 6,2 , Anca L Grosu 1,2 1 Department of Radiation Oncology, University Medical Center, Freiburg, Germany. 2 German Cancer Consortium, Partner Site Freiburg, Freiburg, Germany. 3 German Oncology Center, European University of Cyprus, Limassol, Cyprus. 4 Department of Nuclear Medicine, University Medical Center, Freiburg, Germany. 5 Department of Radiology, University Medical Center, Freiburg, Germany. 6 Department of Radiation Oncology - Division of Medical Physics, University Medical Center, Freiburg, Germany. 7 Department of Urology, University Medical Center, Freiburg, Germany. 8 Department of Radiation Oncology, Charité – Universitätsmedizin Berlin, Berlin, Germany Purpose/Objective: The HypoFocal Phase II trial investigates the safety and feasibility of focal dose escalation in moderately hypofractionated radiotherapy (MHRT) and high-dose-rate brachytherapy combined with external beam RT (HDR BT+EBRT) for prostate cancer (PCa) based on fcuntional imaging with multiparametric magent resonance tomography (mpMRI) and positron emission tomography targeting prostate specific membrane antigen (PSMA-PET). Here we present the primary endpoint results, toxicities and quality of life (QoL) after follow up (FU) of two years. Material/Methods: Intermediate and high risk PCa patients were treated with MHRT of 60 Gy in 20 fractions and a focal boost of up to 75 Gy in Arm A, or HDR-BT of 15 Gy to the whole gland with a boost of up to 19 Gy, followed by EBRT of 44 Gy in 20 fractions in Arm B. Boost was defined by both, mpMRI and PSMA-PET. Genitourinary (GU) and gastrointestinal (GI) toxicities were assessed according to Common Toxicity Criteria for Adverse Events (version 5.0) criteria. Quality of life was assessed with the International Prostate Symptom Scale (IPSS), and prostate-specific European Organization for Research and Treatment of Cancer (EORTC) questionnaires QLQ-PR25 and QLQ-PR30. Results: 25 patients were treated MHRT with a median FU of 35 months and 30 patients with HDR-BT+EBRT with a median FU of 31 months. At two year FU the rate of grade 2+ GI and GU toxicity was 24% and 8% in Arm A and 10% and 0% in Arm B, respectively. Two grade 3 GI toxicities were reported in Arm A, which can be attributed to multifactorial genesis and interventions. QoL of life was good with significant and minimally important differences only in bowel symptoms in Arm A and sexual functioning in Arm B. One patient in each arm relapsed. Figure 1 and 2 demonstrate GU and GI toxicities as well as QoL form MHRT (A) and HDR-BT (B).