ESTRO 2025 - Abstract Book

S1121

Clinical – Head & neck

ESTRO 2025

and severity grading across specialties emphasize the need for standardized imaging protocols and specialist training with highlighted value of multimodality imaging.

Keywords: osteoradionecrosis, HNC, radiographic detection

References: 1. Frankart AJ, Frankart MJ, Cervenka B, Tang AL, Krishnan DG, Takiar V. Osteoradionecrosis: Exposing the Evidence Not the Bone. International Journal of Radiation Oncology Biology Physics. 2021;109(5):1206-1218. doi:10.1016/j.ijrobp.2020.12.043 2. Watson EE, Hueniken K, Lee J, et al. Development and Standardization of an Osteoradionecrosis Classification System in Head and Neck Cancer: Implementation of a Risk-Based Model. J Clin Oncol. 2024;42(16):1922-1933. doi:10.1200/JCO.23.01951 3. Peterson DE, Koyfman SA, Yarom N, et al. Prevention and Management of Osteoradionecrosis in Patients With Head and Neck Cancer Treated With Radiation Therapy: ISOO-MASCC-ASCO Guideline. JCO. 2024;42(16):1975 1996. doi:10.1200/JCO.23.02750

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Digital Poster Outcomes of proton therapy in the treatment of sinonasal cancers: a single-center experience. Anna Maria Camarda 1 , Rossana Ingargiola 1 , Sara Ronchi 1 , Maria Bonora 1 , Barbara Vischioni 1 , Giulia Fontana 1 , Ester Orlandi 1,2 1 Radiation Oncology Unit, Clinical Department, CNAO National Center for Oncological Hadrontherapy, Pavia, Italy. 2 Department of Clinical, Surgical, Diagnostic, and Pediatric Sciences, University of Pavia, Pavia, Italy Purpose/Objective: Sinonasal cancers (SNCs) pose a challenge for radiation oncologists due to their close proximity to critical organs at risk (OARs), such as the optic nerves and brain, as well as their advanced stage at diagnosis 1 . Proton therapy (PT), with its favorable dosimetric characteristics, offers potential benefits in the multidisciplinary treatment of this disease 2,3 . Our aim is to assess the outcomes of a cohort of patients (pts) with SNCs treated with PT. Material/Methods: A cohort of 56 pts with SNCs treated from July 2017 to November 2022 with PT were included in this retrospective analysis. Mixed beam treatments and adenoid-cystic histology were excluded. Local Relapse Free Survival (LRFS) and Progression Free Survival (PFS) at 2-years (2-y) were evaluated with the Kaplan Meier. Univariable analysis was performed with Log-Rank test to evaluate the association of clinical and treatment variables with the survival outcomes. Toxicity grading was assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v5. Univariable analysis (chi-squared and Mann-Whitney U tests) was used in order to identify clinical and treatment factors impacting acute and late G2+ toxicities. Results: Squamous cell carcinoma was the most frequent histology (34%), followed by Intestinal type adenocarcinoma (27%). Thirty-eight pts (68%) underwent surgery followed by PT. Thirty-one pts (55.3%) were treated with induction and/or concomitant chemotherapy. PT was delivered to all pts with a median total dose of 66 Gy RBE (range 60-70 Gy RBE). With a median follow-up time of 28 months (95% CI: 25.16-35.8) 2-y LRFS achieved 79.6% (95% CI: 68.9– 91.8%) and 2-y PFS was 67.8% (95% CI: 56.2-81.7%) (Fig. 1). At univariate analysis, 2-y PFS was significantly better for T2-T3 stage vs T4 (p = 0.045). Dose < 69.96 Gy RBE was associated with better 2-y PFS and 2-y LRFS (p= 0.003 and p = 0.005). Acute and late max G2+ toxicity were respectively 74% and 48%. No G4 acute toxicity was reported. One late G4 toxicity was expected due to the involvement of the optic nerve by the disease.