ESTRO 2025 - Abstract Book

S1662

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

335

Digital Poster Outcomes after extracorporeal irradiation in patients with primary malignant bone tumors Edona Dreshaj 1 , David Patin 2 , Maud Marguet 2 , Raphael Moeckli 2 , Antonia Digklia 3 , Fernanda Gabriela Herrera 4 , Stéphane Cherix 5 , Rémy Kinj 4 1 Faculté de biologie et de médecine, Unil, Lausanne, Switzerland. 2 Service of Radiotherapy, Institution of radio physics, Lausanne, Switzerland. 3 Medical oncology, CHUV, Lausanne, Switzerland. 4 Service of Radiotherapy, CHUV, Lausanne, Switzerland. 5 Department of Orthopaedics and Traumatology, CHUV, Lausanne, Switzerland Purpose/Objective: Bone sarcoma curative treatment is usually based on en-bloc radical surgery. The implementation of extracorporeal irradiation (ECI) made it possible to treat patients with primary malignant bone tumors with limb sparing. The treatment consists of en-bloc resection, followed by autograft recycling performing ECI and reimplanting the bone in the body. We evaluated the oncological and functional outcomes after this procedure. Material/Methods: This retrospective single institution study included patients with primary malignant bone cancer who were treated with en-bloc resection followed by ECI and reimplantation between December 2016 and February 2024. Ethical approval : CER-VD_2024-01221 Results: Twenty patients were included; 13 males and 7 females with a median age of 38 years (min-max range: 18-80). Chondrosarcoma (N=10, 50%), osteosarcoma (N=4, 20%) and Ewing’s sarcoma (N=3, 15%) were the main histological types. The most frequently treated site was pelvis (N=11, 55%), the upper limbs (N=5, 25%) and the lower limbs (N=3, 15%). All patients underwent an en-bloc excision; then the excised bone received a single fraction of 50 Gy and was reimplanted in its initial position in the body for autograft recycling reconstruction. The median follow up was 17.1 months (min-max range: 2.5-80.6). The overall survival rate at 2 years was 94.4% (CI 95%: 83.8-100). A total of 5 patients experienced a relapse in any site, out of them, 3 patients presented a local relapse, while 2 experienced a distant recurrence in the lungs. Local control at 1 year and 2 years was 100% (CI 95%: 100-100) and 62.5% (CI 95% : 29.1-96.1), respectively. The metastatic free survival rate at 1 and 2 years was 94.4% (IC 95%: 83.8 100) and 82.6% (CI 95%: 15.1-79.1), respectively. Fourteen patients developed postoperative complications. The postoperative complications included orthopedic/ prosthetic problems (N=6, 30%) and neurological pain (N= 4, 20%). The functional outcomes were good to excellent for 12 patients (60%), fair for 4 patients (20%) and failure for 4 patients (20%). After multivariate analysis a bigger tumor size was found as a pejorative factor for local relapse (p=0.02) and patients who underwent surgical re-interventions after the initial surgery had a worst overall survival compared to those who were only surged once (p=0.026).

Conclusion: ECI and autograft recycling reconstruction for patient with primary malignant bone tumors achieved satisfying oncological and functional outcome, permitting an innovative reconstruction technique in limb sparing surgery.

Keywords: Extracorporeal irradiation, bone sarcoma,