S974
Clinical - Oligometastatic cancer
ESTRO 2026
Oncology Ljubljana, Ljubljana, Slovenia. 13 Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia. 14 Department of Radiation Oncology, Ghent University Hospital, Ghent University, Ghent, Belgium. 15 Department of Radiation Oncology, European Institute of Oncology IRCCS, Milan, Italy. 16 Department of Radiation Oncology, AZ Groeninge, Kortrijk, Belgium. 17 Department of Radiation Oncology, Policlinico Universitario Campus Bio-Medico Oncology Center, Rome, Italy. 18 Department of Radiation Oncology, Catharina Ziekenhuis, Eindhoven, Netherlands. 19 Department of Radiation Oncology, Hospital De La Santa Creu I Sant Pau, Barcelona, Spain. 20 Department of Radiation Oncology, Hospital General Universitario Santa Lucia, Murcia, Spain. 21 Department of Radiation Oncology, University Hospital Hradec Kralove, Hradec Kralov, Czech Republic. 22 Department of Radiation Oncology, Radiotherapiegroep Locatie Deventer, Deventer, Netherlands. 23 Department of Radiation Oncology, AZORG, Aalst, Belgium. 24 EORTC Headquarters, EORTC, Brussels, Belgium. 25 Department of Radiation Oncology, University Hospital Zurich, University of Zurich, Zurich, Switzerland Purpose/Objective: The anatomical distribution of metastases follows tumor-specific patterns. With advanced imaging,
Conclusion: Across both baseline and recurrence, the emergence of new metastatic foci was associated with poorer survival following SABR. In contrast, patients progressing only in pre-existing lesions achieved prolonged post-progression control and may represent a favorable subgroup for clinical trials targeting salvage SABR or using as a stratification variable. Keywords: Oligoprogression, New vs Pre-existing Metastases Oligometastatic locations: Interim Analysis of the International ESTRO EORTC E2R OligoCare cohort Ines Joye 1,2 , Esmée Looman 3 , Marta Scorsetti 4,5 , Filippo Alongi 6,7 , Umberto Ricardi 8 , Daniela Greto 9 , Pètra Braam 10 , Inga-Malin Simek 11 , Ivica Ratosa 12,13 , Yolande Lievens 14 , Maria Alessia Zerella 15 , Piet Dirix 1 , Karin Stellamans 16 , Sara Ramella 17 , Heike Peulen 18 , Gemma Sancho-Pardo 19 , Juan Salinas Ramos 20 , Igor Sirak 21 , Paul Jeene 22 , Samuel Bral 23 , Lore Meelberghs 24 , Enrico Clementel 24 , Felix Oppong 24 , Matthias Guckenberger 25 , Piet Ost 1 1 Department of Radiation Oncology, Iridium Netwerk, Mini-Oral 2505 Safety and Efficacy of SBRT for Atypical Wilrijk, Belgium. 2 MIPRO, University of Antwerp, Antwerp, Belgium. 3 Department of Radiation Oncology, University Hospital Zurich, Zurich, Switzerland. 4 Department of Biomedical Sciences, Humanitas University Pieve Emanuele, Milan, Italy. 5 Department of Radiotherapy and Radiosurgery, IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy. 6 Department of Radiation Oncology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar, Italy. 7 Department of Biomedical Sciences, University of Brescia, Brescia, Italy. 8 Department of Radiation Oncology, University of Turin, Turin, Italy. 9 Radiotherapy Unit, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. 10 Department of Radiation Oncology, Radboud University Medical Center Nijmegen, Nijmegen, Netherlands. 11 Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria. 12 Division of Radiotherapy, Institute of
metastases in atypical anatomical sites are increasingly detected. This study describes
dissemination patterns of the four most prevalent primary malignancies and evaluates the safety and efficacy of stereotactic body radiotherapy (SBRT) for oligometastases at atypical sites. Material/Methods: OligoCare is a prospective observational cohort study within the EORTC-ESTRO E2RADIatE platform enrolling patients with oligometastatic non-small cell lung cancer (NSCLC), breast, colorectal and prostate cancer, treated with radical-intent SBRT. Descriptive statistics characterized the anatomical distribution of SBRT- treated lesions per tumor type. Metastatic sites other than lung, liver, bone, brain and non-regional lymph nodes were classified as atypical. Grade ≥ 3 adverse events (AEs) and local (in-field) progression -defined as recurrence within the planning target volume- were analyzed at the patient level. The cumulative incidence of local progression was estimated using the Aalen– Johansen method, accounting for deaths without local progression as competing risks. Results: Between July 2019 and July 2025, 57 international institutions enrolled 2805 patients; 2447 were eligible for analysis, encompassing 3533 lesions. Median follow-up was 31 months. The most frequent metastatic sites were bone for prostate (63%) and breast (58%) cancer, and lung for NSCLC (34%) and
Made with FlippingBook - Share PDF online