S1045
Clinical – Sarcoma, skin cancer, malignant melanoma
ESTRO 2026
normofractionated RT in patients with etSTS. Keywords: Margins, Radiotherapy, CTV
Radiation Oncology, Stanford University, Palo Alto, USA. 16 Department of Surgery, Duke University, Durham, USA. 17 Department of Pathology, Stanford University, Palo Alto, USA. 18 Department of Orthopaedic Surgery, Duke University, Durham, USA. 19 Division of Medical Oncology, Department of Medicine, Duke University, Durham, USA. 20 Department of Radiotherapy and Radiation Oncology, Princess Margaret Cancer Centre, Toronto, Canada Purpose/Objective: Data guiding optimal radiotherapy (RT) target volume margins for extremity/truncal soft tissue sarcoma (etSTS) are limited. We evaluated recurrence patterns and treatment-related toxicity in patients with grade 2- 3 etSTS treated with preoperative RT with or without pembrolizumab and reduced clinical target volume (CTV) margins (3 cm longitudinal, 1.5 cm radial) in the randomized SU2C-SARC032 trial. Material/Methods: We centrally reviewed individual RT treatment plans to assess margin expansion in patients with grade 2-3 undifferentiated pleomorphic sarcoma (UPS), myxofibrosarcoma deep to fascia (MFS), dedifferentiated liposarcoma, and pleomorphic liposarcoma from the SU2C-SARC032 trial. Patients received preoperative RT (50 Gy in 25 fractions) with or without pembrolizumab. Local recurrences were classified as in-field, marginal, or out-of-field, and toxicities were prospectively recorded per CTCAE 4.0. Results: Among 105 patients with evaluable RT plans (75.2% intensity-modulated RT), UPS (77.1%) and MFS (11.4%) predominated, 64.8% had grade 3 tumors, 68.6% lower limb etSTS, with a median tumor size of 10 cm. Central review confirmed protocol-specified median gross tumor volume (GTV)-to-CTV expansion (3.0 cm longitudinal and 1.5 cm radial, including edema, anatomically constrained), and a 0.5 cm CTV-to- planned target volume (PTV) margin. After a median follow-up of 54.3 months, two local recurrences (1.9%) occurred, both within the PTV (in-field recurrence) after R0 resection in the pembrolizumab arm. Wound complications according to CTCAE occurred in 19 patients (18.1%), including 16 of 72 (22%) lower extremity cases. At 2 years, at least one grade ≥ 2 late toxicity occurred in 15 (14.3%) of patients, including subcutaneous fibrosis (4.8%), edema (7.6%), fractures (2.9%), and joint stiffness (1%). Conclusion: Consistent with the RTOG 0630 trial, SU2C-SARC032 demonstrated that preoperative RT with a 3 cm longitudinal and 1.5 cm radial GTV-to-CTV expansion achieves effective local control with low late toxicity. These findings support the adoption of these target volume margins for delivering preoperative
Poster Discussion 3479
Skin Cosmesis Assessment Tools for Patients with Keratinocyte Carcinoma: A Systematic Review on Behalf of the ESTRO Skin and Soft Tissue Focus Group Romaana Mir 1 , Marcin Miszczyk 2,3 , Tomasz Krzysztofiak 4 , Bruno Fionda 5 , Vassilios Vassiliou 6 , Agata Rembielak 7,8 1 Mount Vernon Cancer Centre, East and North Hertfordshire Teaching NHS Trust, Northwood, United Kingdom. 2 Comprehensive Cancer Centre, Medical University of Vienna, Vienna, Austria. 3 Department of Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel, Germany. 4 Brachytherapy Department, Maria Sk ł odowska-Curie National Research Institute of Oncology, Gliwice, Poland. 5 Department of Radiation Oncology, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy. 6 The Radiation Oncology Clinic, Bank of Cyprus Oncology Center, Strovolos, Cyprus. 7 Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom. 8 Division of Cancer Sciences, The University of Manchester, Manchester, United Kingdom Purpose/Objective: Keratinocyte carcinoma (KC) are highly prevalent localised skin cancers which rarely impact on mortality. Post-treatment cosmesis, described as “how good the skin looks”, is paramount as the sequelae of treatment are visible and impact social functioning. There is no consensus on reporting post-treatment cosmesis, which precludes standardised cosmesis comparisons between treatments. We conducted this systematic review on behalf of ESTRO Skin and Soft Tissue Focus Group and endorsed by the ESTRO Professions and Partnerships Council to synthesise data on how cosmesis is assessed and reported. Material/Methods: This systematic review was prospectively registered (PROSPERO:CRD420251020168) and complied with the PRISMA 2020 statement. On 03.04.2025 MEDLINE, Embase, and Web of Science were searched for original studies which included cosmesis assessment following radiotherapy for KC. Data was collated on definition of scales, items used for assessment, and timeframe and methods of cosmesis appraisal. Cosmesis scale reporting were graded as level (1)Categorised against defined parameters, (2)Subjective assessment, (3)Insufficient detail. Results: Seventy-three of the 1034 records were included,
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