ESTRO 2025 - Abstract Book

Brachytherapy - Gastro-intestinal, paediatric brachytherapy, miscellaneous

S189

ESTRO 2025

Keywords: Rectal cancer, HDR brachytherapy, guideline

3851

Mini-Oral Survival and toxicity outcomes of perioperative high-dose-rate brachytherapy in soft tissue sarcomas of the extremities and superficial trunk. Lidia Gómez Perea 1 , Irene Martínez Montesinos 2 , Ignacio Visus Fernández de Manzanos 2 , Lucia Biscari García 2 , Naiara Fuentemilla Urío 3 , Santiago Pellejero Pellejero 3 , Esther Francés Tirapu 2 , Raquel Villanueva Goyeneche 2 , Juan José Sánchez Villares 4 , José Ignacio Sánchez González 4 , Valentín Jorge Baranda Areta 4 , José Manuel López Blasco 4 , Javier Castro García 5 , José Rey Vasalo 5 , Elena Villafranca Iturre 2 1 Radiation Oncology, Hospital Universitario Nuestra Señora de la Candelaria, Santa Cruz de Tenerife, Spain. 2 Radiation Oncology, Hospital Universitario de Navarra, Pamplona, Spain. 3 Radiophysics, Hospital Universitario de Navarra, Pamplona, Spain. 4 Traumatology and Orthopedics, Hospital Universitario de Navarra, Pamplona, Spain. 5 Plastic Surgery, Hospital Universitario de Navarra, Pamplona, Spain Purpose/Objective: To evaluate survival and toxicity outcomes in adults with soft tissue sarcomas (STS) treated with surgery and perioperative high-dose-rate (HDR) brachytherapy (PoBT) at our centre. Material/Methods: A retrospective observational study was conducted. Patients expected to have suboptimal resection margins (<1 cm) were selected for local excision followed by HDR PoBT. Catheters were implanted to cover the surgical bed, and a planning CT scan was performed 3–5 days postoperatively. A total dose of 20 Gy was administered in 5 fractions over the subsequent 3 days. External beam radiotherapy (EBRT) was delivered as a neoadjuvant or adjuvant treatment, with a total dose of 45–50 Gy in 23–25 fractions. Survival and toxicity were assessed through a review of each patient’s medical history. Survival was analysed via the Kaplan-Meier method, risk factors were compared using the log-rank test (SPSS v25), and toxicity was graded according to the CTCAE v5 criteria. Results: A series of 55 patients treated from 2008 to 2023 was analysed. Median follow-up was 100 months (12–197); 3 patients were lost during the first year of follow-up. Median age was 59 years (24–88). Tumour sites: 45 extremities (81.8%) and 10 superficial trunks (18.2%). Tumours were classified as low grade (grade 1) in 24 patients (43.6%) and high grade (grades 2–3) in 31 (56.4%). Tumour size was classified as less than 10 cm (T1–T2) in 27 patients (49.1%) and more than 10 cm (T3-T4) in 28 (50.9%). Regarding surgical margins, negative margins were achieved in 36 patients (65.5%), while positive margins were identified in 19 (34.5%). EBRT was administered preoperatively in 5 patients (9.1%) and postoperatively in 44 (80%). Six patients (10.9%) did not receive EBRT; 3 (5.4%) due to wound healing complications. Chemotherapy was administered to 9 (16.4%) patients. The 5- and 10-year results of the univariate survival analysis were: local control (LC) 84.6% and 79.6%, metastasis free survival (MFS) 74.5% and 70.3%, and overall survival (OS) 64.8% and 51.9%. The survival distribution analysis according to risk factors is shown in Table 1 and Figure 2 . Acute toxicity grade 3 or more occurred in 11 patients (20%). Chronic toxicity grade 3 or more occurred in 4 patients (7.27%).