ESTRO 2025 - Abstract Book

S1695

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

Results: Twenty patients were enrolled in the study, 15 patients had undergone surgery and were included in the analysis. Twelve patients were male, and the mean age was 55 years (range: 19–72 years). Fourteen tumors were located in the limbs. The most common histology was myxoid liposarcoma (26.7%), followed by undifferentiated pleomorphic sarcoma (20%) and extraskeletal dedifferentiated chondrosarcoma (20%). The mean tumor size was 675 cc. Concurrent chemotherapy was administered to two patients (13.3%). During radiotherapy, two patients experienced Grade 3 skin toxicity. Pathological examination revealed that all patients achieved R0 resection. Pathological complete response was observed in two patients (13.3%), while seven patients (46.7%) achieved a pNCR. At a mean time of 71(60-91) days after surgery, two patients developed wound complications requiring vacuum-assisted wound closure, and one patient underwent surgical debridement. Conclusion: Preliminary results from the initial cohort of 15 patients show a favorable safety profile and promising tumor response. References: O'Sullivan B, Davis AM, Turcotte R, Bell R, Catton C, Chabot P, Wunder J, Kandel R, Goddard K, Sadura A, Pater J, Zee B. Preoperative versus postoperative radiotherapy in soft-tissue sarcoma of the limbs: a randomised trial. Lancet. 2002 Jun 29;359(9325):2235-41. doi: 10.1016/S0140-6736(02)09292-9. PMID: 12103287. Salerno KE, Alektiar KM, Baldini EH, Bedi M, Bishop AJ, Bradfield L, Chung P, DeLaney TF, Folpe A, Kane JM, Li XA, Petersen I, Powell J, Stolten M, Thorpe S, Trent JC, Voermans M, Guadagnolo BA. Radiation Therapy for Treatment of Soft Tissue Sarcoma in Adults: Executive Summary of an ASTRO Clinical Practice Guideline. Pract Radiat Oncol. 2021 Sep-Oct;11(5):339-351. doi: 10.1016/j.prro.2021.04.005. Epub 2021 Jul 26. PMID: 34326023 Digital Poster Local control with moderately hypofractionated definitive radiotherapy delivered by simultaneous integrated boost technique in non-extremity sarcomas Jonathan D Towler, Clare David, Olivia Dixon, Franel Le Grange, Avinash Pilar, Beatrice Seddon, Mahbubl Ahmed The London Sarcoma Service, University College London Hospitals, London, United Kingdom Purpose/Objective: Whilst surgery remains the standard of care for non-extremity sarcomas, frequently complete resection cannot be achieved or would result in unacceptable morbidity. Furthermore, in some cases an operation cannot be performed due to patient factors including fitness. Outcome data for definitive radiotherapy in this context are limited. There is growing evidence for hypofractionation in the pre-operative setting for soft tissue extremity sarcomas 1 , an approach supported by pre-clinical radiosensitivity studies 2 . However, there are limited data on the use of hypofractionation at non-extremity sites near sensitive organs at risk. We report our institutional experience delivering hypofractionated definitive radiotherapy (2.2-2.5 Gy per fraction) via a simultaneous integrated boost technique to patients with inoperable non-extremity sarcomas. Material/Methods: Between July 2021 and August 2024, moderately hypofractionated definitive radiotherapy was delivered to 60 patients in 61 treatment courses. Thirty-six (59%) had soft tissue tumours and twenty-five (41%) had high-grade bone tumours. Eleven (18%) received concurrent systemic anti-cancer therapy. The most common dose prescriptions were 63 Gy in 28 fractions, predominantly for soft tissue tumours (35 patients, 57%), and 70 Gy in 28 fractions for bone sarcomas (20 patients, 33%). Keywords: Neoadjuvant radiotherapy, sarcoma, SIB 2734