S2973
Late-Breaking
ESTRO 2026
Radioonkologie und Strahlentherapie, Universitätsmedizin der Johannes Gutenberg- Universität Mainz, Mainz, Germany. 10 Klinik für Strahlentherapie, Schwerin, HELIOS Kliniken Schwerin, Schwerin, Germany. 11 Universitätsklinik für Radioonkologie, Universitätsklinikum Tübingen, Tübingen, Germany. 12 Praxis für Radioonkologie, Johanniter-Zentren für Medizinische Versorgung in Der Altmark, Stendal, Germany. 13 Zentrum für Klinische Studien, Universität zu Lübeck, Lübeck, Germany Purpose/Objective: For patients with oligometastatic disease, the addition of stereotactic radiotherapy has been shown to improve progression-free survival and, in some cases, overall survival. However, two randomized controlled trials have failed to demonstrate any benefit of additional local therapy in patients with oligometastatic breast cancer. Material/Methods: The OLIGOMA trial (ARO-2021-09, NCT04495309) is a randomized controlled, multinational, and multicenter study investigating the efficacy and tolerability of local radiation therapy in patients with oligometastatic breast cancer. Patients with up to 5 metastases of histologically confirmed breast cancer with an indication for palliative systemic drug therapy were included. All metastases had to be amenable to local treatment. Patients were randomized 1:1 to the control group (drug therapy alone, palliative radiation permitted) or the experimental group (additional local therapy for all manifestations, preferably local radiotherapy). Stratification was based on the type and line of palliative systemic therapy. Co-primary endpoints were progression-free survival (PFS; superiority) and quality of life (sum score) 12 weeks after randomization (non-inferiority). The analysis of the endpoints was stratified by concomitant therapy (first- or second-line endocrine therapy vs. first- or second-line chemotherapy). The study was terminated early in June 2025 due to slow recruitment. Results: From March 2021 to April 2024, a total of 87 patients were enrolled and randomized at 31 centers in Germany and Austria. 55.2% of the patients received first-line endocrine therapy. Approximately 70% of the patients had one or two metastases. Progression or death occurred in 39 patients. The median PFS was 20.6 months (95% confidence interval (CI): 12.5–28.6) in the control group and 36.2 months (95% CI: 24.3– not determinable) in the experimental group. A significant advantage in favor of the experimental group was observed for PFS (hazard ratio = 0.48; 95% CI: 0.25–0.92; p = 0.022). The mean difference in health-related quality of life (experimental group – control group), adjusted for the baseline measurement, was − 2.1 points (95% CI: − 9.2–5.1). The
References: Zegers CM, Rekers NH, Quaden DH, Lieuwes NG, Yaromina A, Germeraad WT, Wieten L, Biessen EA, Boon L, Neri D, Troost EG, Dubois LJ, Lambin P. Radiotherapy combined with the immunocytokine L19-IL2 provides long-lasting antitumor effects. Clin Cancer Res. 2015 Mar 1;21(5):1151-60. Epub 2014 Dec 31. Keywords: immunotherapy, randomized trial, Lung cancer, Metastases-directed treatment in Patients with Oligometastatic Breast Cancer: Results from the OLIGOMA-trial (ARO-2021-09, NCT04495309) David Krug 1 , Reinhard Vonthein 2 , Nicole Heßler 2 , René Baumann 3 , Dorit Uhlemann 4 , André Buchali 5 , Johannes Claßen 6 , Ute Maria Ganswindt 7 , Ursula Nestle 8 , Carina Schwanbeck 9 , Sybille Weber 10 , Nicola Weidner 11 , Evelyn Weinstrauch 12 , Kathrin Dellas 1 , Sina Nadine Jeß 13 , Denise Olbrich 13 , Jürgen Dunst 1 1 Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany. 2 Institut für Medizinische Biometrie und Statistik, Proffered Paper 5611 Universitätsklinikum Schleswig-Holstein, Universität zu Lübeck, Lübeck, Germany. 3 Klinik für RadioOnkologie & Strahlentherapie, Marien Gesellschaft Siegen, Siegen, Germany. 4 Klinik für Strahlentherapie und Radioonkologie, Heinrich-Braun-Klinikum Zwickau, Zwickau, Germany. 5 Klinik für Strahlentherapie und Radioonkologie, Universitätsklinikum der Medizinischen Hochschule Brandenburg, Neuruppin, Germany. 6 Klinik für Strahlentherapie, Radiologische Onkologie und Palliativmedizin, ViDia Christliche
Kliniken Karlsruhe,, Karlsruhe, Germany. 7 Universitätsklinik für Strahlentherapie und
Radioonkologie, Medizinische Universität Innsbruck, Innsbruck, Austria. 8 Klinik für Strahlentherapie und Radiologische Onkologie, Kliniken Maria Hilf GmbH, Mönchengladbach, Germany. 9 Klinik und Poliklinik für
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