ESTRO 2025 - Abstract Book

S1723

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

4052

Digital Poster Lattice treatment in inoperable non-extremities soft-tissue sarcomas

Katarina Majercakova 1 , Natalia Tejedor Aguilar 2 , Josep Isern Verdum 1 , Helena Vivancos Bargalló 2 , Antonio Vila Capel 1 , Miriam Mancera Soto 1 , Guillermo Gómez de Segura Melcón 1 , Jady Vivian Rojas Cordero 1 , José Antonio Gonzalez Lopez 3 , Silvia Bagué Rosell 4 , Diana Hernandez Jover 5 , Saba Rabi Mitre 1 , Ana Peiró Ibañez 6 , Ana Sebio García 7 , Gemma Sancho Pardo 1 1 Radiation Oncology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 2 Radiophysics and Radioprotection, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 3 General and Digestive Surgery, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 4 Pathological Anatomy, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 5 Radiology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 6 Orthopaedic Surgery and Traumatology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 7 Medical Oncology, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain Purpose/Objective: Lattice (LRT) is a technique of spatially-fractionated radiotherapy that allows to administer inhomogeneous high doses of radiation (10-20) Gy within the gross tumour. The objective of this study was to evaluate feasibility and acute toxicity. Material/Methods: Our retrospective observational study includes 15 histologically proven inoperable non-extremity sarcoma patients, treated at our institution between 2020-2024. All were treated with standard external beam radiotherapy (EBRT) 45-54Gy/25-20fx Gy,20-25Gy/5fx or 30/10fx and a boost with Lattice technique of 20Gy single dose. No concurrent chemotherapy or immunotherapy were administered. Toxicity was reported according to CTCAEv5.

Results:

Mean follow-up:10 months (4-32). Nine patients were male and 6 females. Median age was 60 years. Eleven were primary tumors and four metastases (1 pelvic,1 retroperitoneal,1 thoracic,1 nodal). Tumor location was following: mediastinum (3), abdomen (7), and pelvis (5). Histology was: condrosarcoma (2), dedifferentiated liposarcoma (4), endometrial stromal sarcoma (1), leiomyosarcoma (2), malignant peripheral nerves heath tumor (1), synovial sarcoma (1), undifferentiated pleomorphic sarcoma (1), undifferentiated spindle cell sarcoma (3). Median GTV volume: 1058 cm³(range 142-6103) .Median number of spheres: 9 (4-30).