ESTRO 2025 - Abstract Book

S1678

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

Results: Five patient cases were discussed resulting in 105 recommendations. Agreement percentages for case 1 to 5 were 14.3%, 61.9%, 33.3%, 52.4% and 14.3%, with a median agreement percentage of 33.3%. Grouping pre- and postoperative therapies as "perioperative" and including recommendations with and without regional hyperthermia raised the median agreement to 47.6%. The mean consensus level within each center across all 5 cases was 9.5. Conclusion: This first case-based analysis of inter-center agreement for STS management in German-speaking countries reveals low inter-center agreement but high intra-center consensus. Our study includes nearly all tertiary sarcoma centers in German-speaking countries, affirming its strong external validity. These findings suggest potential and clinically very relevant differences in treatment standards among sarcoma centers. Enhanced case-based exchanges and collaborative efforts are needed to reduce discrepancies and standardize the management of STS patients.

Keywords: Intercenter agreement, Tumor boards

References: Soft tissue sarcoma, ring trial, reference center, inter-center agreement, German Cancer Society, guidelines

1659

Digital Poster Locally Ablative Treatments in Oligometastatic Sarcoma Patients: A Retrospective Comparison of Surgery and Stereotactic Body Radiotherapy Niccolo' Bertini 1 , Daniela Greto 1 , Mauro Loi 1 , Pietro Garlatti 1 , Vieri Scotti 1 , Luca Visani 1 , Monica Mangoni 1 , Marco Banini 1 , Marianna Valzano 1 , Domenico Andrea Campanacci 2 , Giuliana Roselli 2 , Annarita Palomba 3 , Luisa Caprara 1 , Carolina Orsatti 1 , Ilaria Morelli 1 , Ilaria Bonaparte 1 , Chiara Mattioli 1 , Luca Burchini 1 , Beatrice Bettazzi 1 , Cecilia Petruccioli 1 , Doruntina Cela 1 , Lorenzo Livi 1 1 Radiation Oncology, Azienda Ospedaliero-Universitaria Careggi, Firenze, Italy. 2 Department of Orthopaedic Oncology and Reconstructive Surgery, Careggi University Hospital, Firenze, Italy. 3 Section of Pathological Anatomy, Department of Health Sciences, Azienda Ospedaliero-Universitaria Careggi, Firenze, Italy Purpose/Objective: In oligometastatic sarcoma patients, even if locally ablative treatments (LATs), such as surgery and stereotactic body radiotherapy (SBRT), are utilized to target metastatic lesions, nowadays the optimal treatment modality remains unclear. This study aims to evaluate outcomes of these approaches in a cohort of oligometastatic sarcoma patients treated in one single institution. Material/Methods: Clinical and treatment-related data from consecutive oligometastatic sarcoma patients treated at our Institution between May 2004 and June 2024 were retrospectively reviewed. A total of 69 patients, who underwent LATs either with surgery or SBRT with a biologically effective dose (BED) ≥50 Gy (EQD2), were included. A total of 103 metastases were treated, with the cohort comprising both pulmonary and extrapulmonary lesions. Median dose for SBRT was 35 Gy (range 35-55 Gy) in 3-8 fractions. Local control (LC) rates were assessed at 1 and 3 years. Univariate (UV) analysis was performed to identify factors associated with LC. Results: Sixty-nine patients were included in the analysis, with a total of 103 metastatic lesions treated. Median age at diagnosis was 53 (range 13-81) years. The median interval time from initial diagnosis to metastasis onset was 38.5 months. Seventeen (24.6%) patients underwent metastasectomy, all were treated with SBRT at the time of local and/or distant recurrence. Of the treated lesions, 38.5% (40) were pulmonary and 61.5% (63) were extrapulmonary.