ESTRO 2025 - Abstract Book

S972

Clinical – Head & neck

ESTRO 2025

Purpose/Objective: Although postoperative radiotherapy (RT) is frequently applied to improve local control in head and neck sarcomas, the optimal RT technique remains uncertain. While there is an increasing body of literature on preoperative hypofractionated RT, data on hypofractionated RT in the postoperative period are limited. This study aims to compare the efficacy and toxicity profiles of conventional fractionated RT (CFRT) and stereotactic body RT (SBRT) in patients with head and neck sarcoma who received postoperative RT. Material/Methods: The records of 40 patients (29 soft tissue sarcomas, 11 bone sarcomas) who underwent postoperative CFRT (n=30, 75%) or SBRT (n=10, 25%) between 2000 and 2023 at our department were retrospectively reviewed. SPSS v23.0 was used for all statistical analyses. Results: The demographic characteristics and treatment features of patients in the SBRT and CFRT groups were generally similar (Table 1). The median RT dose was 35 Gy (range, 24–40 Gy/3–5 fractions) for SBRT and 62 Gy (range, 60–70 Gy/25–33 fractions) for CFRT. The median follow-up period was 60 months (range, 4–250 months). Local control rates with SBRT and CFRT were 80% and 73%, respectively (p=0.67). The 5-year overall survival (OS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) rates were 71%, 66%, and 66%, respectively. OS, LRFS, and DMFS rates were similar between the CFRT and SBRT groups (p>0.05). In the multivariate analysis, R2 resection was identified as the only independent negative prognostic factor for OS (HR: 1.3, 95% CI: 0.1– 0.9, p=0.03). For LRFS, both R2 resection (HR: 1.3, 95% CI: 0.1–0.8, p=0.02) and tumor size ≥5 cm (HR: 1.4, 95% CI: 0.03–0.7, p=0.02) were independent negative prognostic factors. The rate of late grade 3 or higher toxicity was 10% (n=4) and was similar between the SBRT and CFRT groups. Among patients who experienced grade 3 or higher late toxicity, 75% had tumors located in the orbit.