S1037
Clinical – Sarcoma, skin cancer, malignant melanoma
ESTRO 2026
Neither RT modality (SRS vs. FSRT) nor treatment intent (definitive vs. adjuvant) had a significant influence on progression rates. In a subgroup analysis of 10 non-irradiated lesions, only 2 lesions showed a clinical response. Conclusion: SRS and FSRT are effective treatments for melanoma brain metastases, providing good local control. However, patients with multiple metastases are at a greater risk of distant intracranial progression. This highlights the need for personalized, lesion-targeted radiotherapy combined with immunotherapies. References: Davies MA et al. Cancer 2011;117:1687.Sampson JH et al. J Neurosurg 1998;88:11.Minniti G et al. IJROBP 2016;95:1142.Lehrer EJ et al. Int J Mol Sci 2018;19:3054.Lancellotta V et al. Radiol Med 2022;127:773.Gallo J et al. Clin Oncol 2022;34:179.Garimall S et al. J Neurooncol 2020;146:357.Thompson JF et al. Radiol Oncol 2022;56:267.Frakes JM et al. J Neurosurg 2015;123:1261.Ostheimer C et al. Int J
L et al. Radiotherapy to Control Limited Melanoma Progression Following Ipilimumab J Immunother. 2016;39:373-378. Keywords: ICI rechallenge, abscopal effect, overall survival Digital Poster 1833 Stereotactic radiotherapy for malignant melanoma brain metastases in the immunotherapy era and the response rates of non-irradiated lesions Kerem Tuna Tas 1 , Khaled Elsayad 1 , Philipp Lisheswki 1 , Fatima Frosan Sheikhzadeh 1 , Edgar Smalec 1 , Lisa Krönig 2 , Martin Gschnell 2 , Klemens Zink 1 , Hilke Vorwerk 1 , Sebastian Adeberg 1 , Ahmed Gawish 1 1 Radiation Oncology, Marburg University Hospital, Marburg, Germany. 2 Department of Dermatology and Allergology, Marburg University Hospital, Marburg, Germany Purpose/Objective: Malignant melanoma often leads to brain metastases, which present significant treatment challenges. This study examines the clinical outcomes of patients treated with stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) and identifies factors related to disease progression. Material/Methods: This retrospective study included 48 patients with melanoma brain metastases treated with SRS or FSRT between 2016 and 2024. Treatment planning was based on CT and contrast-enhanced MRI with 1–2 mm slices. GTV was defined on MRI; PTV margins were 1–2 mm (SRS) or 2–5 mm (FSRT). Radiation was delivered via linear accelerator with 2 mm micro-MLC. FSRT was preferred for lesions > 2 cm or near ventricles. Corticosteroids were given before treatment; follow- up MRIs were performed every three months. Results: The median age at first radiotherapy (RT) was 56 years (range: 22–88). Among all lesions, 74% were treated with SRS and 26% with FSRT. Most lesions (76%) had not received prior RT, and 22 lesions (21%) had undergone surgical resection. Systemic therapy (ST) was administered concurrently in 83% of lesions, including immunotherapy (IT) in 29%. Lesions were predominantly located in the supratentorial region (91%). The mean follow-up duration was 23 months. In-field progression occurred in 4% of cases, with a mean time to progression of 8 months. Out-of-field progression occurred in 36% of cases, with a mean time of 12 months. Multivariate Cox regression identified the presence of multiple metastases as the only significant predictor of increased out-of-field progression risk (HR = 3.8; 95% CI: 1.5–9.76; p = 0.005).
Oncol 2015;46:2439.Iorio-Morin C et al. J Neurosurg 2014;121 Suppl:69.Gabani P et
al. Radiother Oncol 2018;128:266.Lens M, Schachter J. Curr Treat Options Oncol 2025;26:36.Grimaldi AM et al. Oncoimmunology 2014;3:e28780.Patel RR et al. Radiother Oncol 2021;162:60.Zhang Z et al. Signal Transduct Target Ther 2022;7:258. Keywords: brain metastases Poster Discussion 2064 Real-World Outcomes of Chordoma and Chondrosarcoma Treated with Proton Beam Therapy at a National UK Centre. Mariam Ebrahim, Yuwei Wang, Mohamed Khalid Abutaleb, Abiola Famtimilehin, Hanis Hanafi, Shweta Sharma, Mohamed Elsharief, Venkata Krishna Vamsi Gade, Sanjay Rangegowda, Mark Reed, Anna France, Simeon Aguedu, Kate Robertson, James Wylie The proton beam therapy centre, The Christie NHS, Manchester, United Kingdom Purpose/Objective: To evaluate clinical outcomes, local control, and toxicity in patients with non–base of skull (non-BoS) chordoma and chondrosarcoma treated with proton beam therapy (PBT) at The Christie Proton Beam Therapy Centre since its opening in December 2018. Material/Methods: This retrospective analysis included patients with histologically confirmed chordoma or chondrosarcoma treated with PBT between December 2018 and September 2025. Patients received definitive, preoperative, or postoperative PBT as per
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