ESTRO 2025 - Abstract Book

S1803

Clinical – Upper GI

ESTRO 2025

Conclusion: In patients with inoperable esophageal cancer unfit for standard chemoradiotherapy, radical hypofractionated radiotherapy combined with capecitabine appeared feasible according to predefined criteria. However, it led to grade ≥3 toxicity in 57% of patients and poor survival. Therefore, the regimen should not be advised in clinical practice and continuation to a phase III study is not indicated.

Keywords: chemoradiotherapy, survival, esophageal cancer

2543

Proffered Paper Outcomes of patients with liver oligometastases treated with MRI- or cone-beam CT-guided SBRT from MOMENTUM and OligoCare studies Julia E Peltenburg 1 , Astrid van der Horst 1 , Rana Bahij 2 , Simon Böke 3 , Pètra M Braam 4 , John P Christodouleas 5 , Matthias Guckenberger 6 , William A Hall 7 , Martijn PW Intven 8 , Tomas M Janssen 1 , Corrie AM Marijnen 1 , Luca Nicosia 9 , Piet Ost 10 , Ivica Ratosa 11,12 , Marta Scorsetti 13,14 , Jan-Jakob Sonke 1 , Umberto Ricardi 15 , Helena M Verkooijen 8 , Marlies E Nowee 1 , Filippo Alongi 9,16 1 Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, Netherlands. 2 Department of Oncology, Odense University Hospital, Odense, Denmark. 3 Department of Radiation Oncology, Tübingen University Hospital, Tübingen, Germany. 4 Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, Netherlands. 5 Medical Affairs and Clinical Research, Elekta AB, Stockholm, Sweden. 6 Department of Radiation Oncology, University Hospital of Zurich, Zurich, Switzerland. 7 Department of Radiation Oncology, Froedtert & the Medical College of Wisconsin, Milwaukee, USA. 8 Division of Imaging and Oncology, University Medical Center Utrecht, Utrecht, Netherlands. 9 Advanced Radiation Oncology Department, IRCCS Sacro Cuore Don Calabria Hospital, Verona, Italy. 10 Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium. 11 Division of Radiotherapy, Institute of Oncology Ljubljana, Ljubljana, Slovenia. 12 Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia. 13 Radiosurgery and Radiotherapy Department, IRCCS-Humanitas Research Hospital, Milan, Italy. 14 Department of Biomedical Sciences, Humanitas University, Milan, Italy. 15 Department of Oncology, University of Turin, Turin, Italy. 16 -, University of Brescia, Brescia, Italy Purpose/Objective: Stereotactic body radiation therapy (SBRT) for liver oligometastases shows potential for achieving high local control (LC). However, optimal image guidance and dose schedule remain debated. This study aims to assess LC for patients treated with either MRI- or cone-beam CT (CBCT)-guided SBRT and explore tumor- and treatment-related factors associated with clinical outcome. Material/Methods: Data from two prospective, international registries, MOMENTUM (MR-Linac Consortium; NCT04075305; all MRI guided) [1] and OligoCare (EORTC-ESTRO; NCT03818503; mostly CBCT-guided) [2], were used to include patients treated with liver SBRT. Inclusion criteria: MRI or CBCT guidance; if alive, at least one follow-up moment. Exclusion criteria: proton therapy; missing/insufficient (baseline) data; registry inclusion <12 months prior. The planned isodose covering 98% of the PTV (D98) was converted to biologically effective dose (BED 98 ), with α/β=1.5Gy (primary tumor origin: prostate), 2.5Gy (breast), or 10Gy (all others). Kaplan-Meier analyses were performed for LC and overall survival (OS), with local recurrence defined as recurrence/progression within the PTV. Endpoints: 1-/2-year LC (primary); 1-/2-year OS (secondary). Uni- and multivariable Cox regression for LC/OS included the covariates image guidance modality (CBCT vs. MRI), planned BED 98 (≤100 vs. >100Gy), primary tumor type, CTV and number of treated lesions (N lesions : 1 vs. >1). Significance level α=0.05.