ESTRO 2025 - Abstract Book

S1688

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

Median follow-up was 103 months. 13.9% experienced relapse: 2 (3%) relapses in the irradiated field, 1 (1%) relapse at the margin of the field, 1 (1%) relapse in homolateral eyelid, 1 (1%) relapse on the homolateral skin of the face, and 4 (7%) relapses in the contralateral hemiface. Among the lesions that were not surgically treated and received 42Gy/6f, there was one relapse in the irradiation field and one relapse at the edge of the field. One patient developed distant metastatic relapse after chemotherapy for melanoma, which led to death. A total of 53.4% of patients have died, but only one death was related to the disease (melanoma initially). The median time between surgery and contact therapy was 2.4 months. 20% (14 patients) were lost to follow-up. 23% of patients experienced Grade I/II acute conjunctivitis and 75% had Grade I/II acute erythema. 19.4% had Grade I eye watering. The most frequent sequelae were persistent eye watering ( 26%) and xerosis (20.8%). The majority of patients assessed were very satisfied with both the cosmetic and functional outcomes following radiotherapy. Conclusion: CXT therapy of the eyelid for skin carcinoma is an effective treatment, with few significative side effects or sequelaes in this elderly population.

Keywords: contactherapy, eyelid carcinoma, skin

2433

Mini-Oral Proton therapy in patients with thoracic Ewing sarcomas; Early Result from the Prospective Registry Studies KiProReg and ProReg Christine Hansel 1 , Theresa Steinmeier 1 , Yi-Lan Lin 1 , Sandija Plaude 1 , Christoph Blase 2 , Stephan Tippelt 3 , Sergiu Scobioala 4 , Sebastian Bauer 5 , Uta Dirksen 3 , Beate Timmermann 1,6 1 Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), Essen, Germany. 2 AnästhesieNetz Rhein-Ruhr, Westenfelder Str. 62/64, 44867 Bochum, Germany. 3 University Hospital of Essen, Pediatrics III, Pediatric Hematology and Oncology, Essen, Germany. 4 Department of Radiation Oncology, Münster University Hospital, Münster, Germany, West German Cancer Centre (WTZ), Münster, Germany. 5 Department of Internal Medicine, University Hospital Essen, West German Cancer Center (WTZ), Sarcoma Center Essen, Essen, Germany. 6 German Cancer Consortium, (DKTK), Essen/Düsseldorf, Germany Purpose/Objective: For thoracic Ewing sarcoma (thEwS), surgery is the mainstay of local therapy, commonly combined with radiotherapy (RT) to the hemithorax, whole lung or locally. Proton therapy (PT) can advantageously be used to best spare critical organs at risk, even in large target volumes. Definitive RT is typically applied if the tumor is considered unrespectable. Within this analysis, we report on the outcome of patients with thEwS treated with PT. Material/Methods: This study was approved by the local ethical committee (24-11911-BO) and data was collected from the prospective registry studies KiProReg and ProReg (DRKS00005363, DRKS00004384). Patients enrolled with thEwS between May 2013 and October 2023 were eligible for retrospective analysis. All patients received PT. Data on patient, treatment, tumor outcome and adverse events according to Common Terminology Criteria for Adverse Events v4.0 was prospectively collected. Results: 37 patients were considered for analysis comprising 28 children (75.7%) and nine adults with a median age of 14.7 years (range 1.9-53.4 years) and a comparable gender ratio (20 males, 17 female). Seven patients (18.9%) demonstrated with an extra osseous tumor origin. Four patients presented with metastatic disease before PT (n=3 lung, n=2 bone, n=1 ovary). Gross total and subtotal resection was achieved in 20 and 12 patients (32.4%), respectively. All patients received upfront chemotherapy, additionally, 24 patients received concomitant