S972
Clinical - Oligometastatic cancer
ESTRO 2026
competing-risk analyses. Median follow-up for this update was 54.2 months (previously 25 months). Results: A total of 380 patients were treated (median age 69 years; 32% female). The most common primary cancers were prostate (32%), colorectal (17%), breast (11%), and lung (9%). Oligoprogressive disease accounted for 16%, induced oligometastatic disease for 13%, and synchronous disease for 24%. Most patients (91%) had one or two lesions treated. Updated toxicity analysis demonstrated crude per- patient rates of grade 2 = 18.4%, grade 3 = 5.8%, grade 4 = 0.0%, and grade 5 = 0.3%. There were no additional treatment-related deaths from the originally reported patient who received SABR near their hepatobiliary tree. The most frequent grade ≥ 3 toxicities were pain (1.3%), fracture (2.6%), dyspnea (0.5%), nausea (0.5%), pneumonitis (0.3%), and neuropathy (0.3%). The cumulative incidence of grade ≥ 2 and ≥ 3 toxicity at 5 years was 24% and 7%, respectively. As secondary endpoints, median OS was 64.6 months (95% CI 61.0– 68.1) and median PFS 14.6 months (95% CI 11.6–17.6). Five-year OS, PFS, and LC were 58.6%, 20.3%, and 85.1%, respectively.
meeting the predefined trial goal of achieving a ≥ 30% reduction. Its implementation improves patient convenience and decreases workload of OART while offering clinical benefits. Keywords: OART, Hypofractionation, Oligometastases Proffered Paper 2328 Five-Year Follow-Up of the SABR 5 Trial: Primary Toxicity Analysis of Stereotactic Ablative Radiotherapy for Up to Five Oligometastases Robert A Olson 1,2 , Hadassah Abraham 3 , Deepa Gautam 2 , Mitchell Liu 4 , Alanah Bergman 5 , Benjamin Mou 6 , Hannah Carolan 4 , Will Jiang 7 , Curtis LeClerc 8 , Devin Schellenberg 7 , Abraham Alexandar 9 , Siavash Atrchian 6 , Clement Ho 4 , Islam Mohamed 6 , Angela Lin 6 , Tanya Berrang 9 , Andrew Bang 4 , Nick Chng 10 , Quinn Matthews 10 , Howard Pai 9 , Shilo Lefresne 4 , Sarah Baker 7 1 Surgery, University of British Columbia, Vancouver, Canada. 2 Radiation Oncology, BC Cancer, Prince George, Canada. 3 Clinical Trials, BC Cancer, Prince George, Canada. 4 Radiation Oncology, BC Cancer, Vancouver, Canada. 5 Medical Physics, BC Cancer, Vancouver, Canada. 6 Radiation Oncology, BC Cancer, Kelowna, Canada. 7 Radiation Oncology, BC Cancer, Surrey, Canada. 8 Medicince, University of British Columbia, Prince George, Canada. 9 Radiation Oncology, BC Cancer, Victoria, Canada. 10 Medical Physics, BC Cancer, Prince George, Canada Purpose/Objective: SABR-5 was a provincially coordinated, single-arm, phase II trial designed in British Columbia (BC), Canada, as a bridge between SABR-COMET and the phase III SABR-COMET-3 and -10 trials. The study aimed to safely implement stereotactic ablative radiotherapy (SABR) across all six BC Cancer centres within a unified quality-assurance and peer-review framework, and to quantify treatment-related toxicity on a population basis (primary endpoint). This updated analysis reports extended follow-up and long- term toxicity outcomes, with secondary survival endpoints. Material/Methods: Adults with up to five extracranial metastases (oligometastatic or oligoprogressive) were enrolled between November 2016 and July 2020. During this period, SABR for these indications was available in BC only through this trial. The primary endpoint was SABR-related grade 2–5 toxicity (CTCAE v4.0). Secondary endpoints included overall survival (OS), progression-free survival (PFS), and local control (LC). All grade ≥ 3 events were centrally reviewed by a provincial committee. Survival and toxicity were estimated using Kaplan–Meier and local control by
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