ESTRO 2025 - Abstract Book

S1927

Clinical - Urology

ESTRO 2025

1166

Digital Poster Metastasis directed-SBRT for oligometastatic HSPC: initial patient characteristics of a prospective randomized phase III trial, METRO NCT04983095 Karin Söderkvist 1 , Adalsteinn Gunnlaugsson 2 , Andreas Josefsson 1,3 , Bjørg Aksnessæther Aksnessæther 4 , Chunde Li 5 , Camilla Thellenberg Karlsson 1 , David Kudrén 6 , Erik Lundin 7 , Gabriel Moise 8 , Jenny Kahlmeter Brandell 7 , Jon Kindblom 9 , Joakim Jonsson 1 , Kirsten Björnlinger 8 , Kristin Karlsson 10,11 , Katrin Riklund 1 , Martina Westin 12 , Mattias Hedman 13 , Sara Strandberg 14 , Pernilla Wikström 15 1 Diagnostics and Intervention, Umeå University, Umeå, Sweden. 2 Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund University, Lund, Sweden. 3 Wallenberg center for molecular medicine, Umeå University, Umeå, Sweden. 4 Department for cancer and rehabilitation Ålesund Hospitalt of Diagnostics and Intervention, Helse Møre and Romsdal Hospital Trust, Ålesund, Norway. 5 Clinical Science and Education, Karolinska Institute, Stockholm, Sweden. 6 Oncology, Stockholm South General Hospital, Stockholm, Sweden. 7 Oncology, Örebro University Hospital, Örebro, Sweden. 8 Oncology, County hospital Ryhov, Jönköping, Sweden. 9 Oncology, Clinical Sciences, Sahlgrenska Academy at Gothenburg University, Gothemburg, Sweden. 10 Radiotherapy Physics and Engineering, Karolinska University Hospital, Stockholm, Sweden. 11 Oncology-Pathology, Karolinska Institute, Stockholm, Sweden. 12 Oncology, Capio Saint Göran’s Hospital, Stockholm, Sweden. 13 Radiation Oncology, Karolinska University Hospital, Stockholm, Sweden. 14 Diagnostics and Intervention, Radiology, Umeå University, Umeå, Sweden. 15 Department of Medical Biosciences, Umeå University, Umeå, Sweden Purpose/Objective: Metastasis directed (MD)-SBRT for recurrent oligo metastatic hormone sensitive prostate cancer (omHSPC) has shown promising results for prolonging disease progression (1), but high-grade evidence is lacking. Moreover, the value of MD-SBRT in patients with de novo omHSPC has not been investigated, nor the impact in patient outcome of 1-3 metastases detected by PSMA-PET/CT. The objective of the METRO-trial is to compare failure free survival (FFS) for patients receiving MD-SBRT in addition to standard of care (SoC) with SoC alone in patients with PSMA-PET/CT detected omHSPC. Here, we describe the patient characteristics of the first 50 patients included. Material/Methods: METRO is a prospective, multicenter, randomized trial aiming to recruit 118 patients diagnosed with either de novo or recurrent omHSPC. Strata are de novo/recurrent and M1a/M1b disease. Key inclusion criteria is 1-3 distant metastases with PSMA-RADS score 4-5 (2). All patients receive 3 years of ADT and, from 2023, 2 years of androgen receptor pathway inhibitor (ARPI) (3). In patients with de novo omHSPC, definitive RT to the prostate +/- pelvic fields is delivered. For patients with recurrence, PSMA-PET-positive lesions in the pelvis are treated with salvage RT in the intervention arm. The MD-SBRT is delivered either as 10 Gy x 3 or 8 Gy x 5 every-other-day (eod). Primary endpoint is biochemical FFS. Secondary endpoints include late toxicity, quality of life (QoL), and CRPC. A renewed PSMA-PET/CT is performed at biochemical progression and subsequent treatments will be recorded. The PSMA-PET/CTs are collected, as well as blood and tissue, for exploratory analysis of potential biomarkers for outcome/treatment prediction. Results: The trial opened in October 2021 at a single site. During 2023/2024 six additional sites were opened, and two more Scandinavian sites have ethical approval to participate. Of the first 50 patients, 19 (38%) had de novo and 31 (62%) recurrent disease. For the recurrent patients, 17 (55%) patients had undergone prior prostatectomy and 14 (45%) had previous definitive RT. Approx. half of the patients were included in the trial with lesions scored PSMA-RADS 5 and only 4 (8%) patients had lymph node metastases only. The majority of the patients (57%) had one MD-SBRT-target and only 7% had three.