S531
Clinical – Head & neck
ESTRO 2026
2nd to 4th week of radiation treatment to assess the response to radiation. PET-CT response was assessed using SUV max, patients with a drop of 50% or more in SUV max between interim and initial imaging were considered good responders. All other patients were considered poor responders. All patients completed 60Gy/30 fractions IMRT/VMAT then according to result of interim PET CT and DW MRI, good responders received SBRT 7Gy in single fraction to the residual GTV while poor responsders received SBRT 14 Gy in 2 fractions to residual GTV. Results:
94.1]. After a follow up of 6 months 75 of 96 (78.1%) patients had grade 0 and 1 dysphagia and showed a median EAT-10 score of 6, whereas patients with a dysphagia grade 2 or higher (21.9 %) showed a median EAT-10 score of 26.Dysphagia decreased over time. 27 months after therapy only 10 of 93 (10.8%) were diagnosed with a dysphagia grade 2 or higher with a median EAT-10 Score of 20.5. Patients with dysphagia grades 0 and 1 (89.2%) showed a median EAT-10 score of 3. Conclusion: Omitting contralateral neck irradiation in a predefined patient population was associated with high long term locoregional tumor control, low rates of dysphagia, and a good quality of life. References: Haderlein et al., DOI 10.3389/fronc.2024.1447123 Keywords: deintensification, long term & functional outcomes Interim functional imaging response assessment as a guide for adaptive SBRT dose escalation in HNSCC; A Prospective Phase 2 clinical trial Roa Eltagy 1 , Tarek Shouman 1 , Ashraf Hassouna 1 , Esraa Elkhouly 2 , Ayda Youssef 3 , Maha Hassan 4 , May Ashour 1 1 Radiation Oncology department, National Cancer InstituteCairo University, Cairo, Egypt. 2 Nuclear Medicine Departement, National Cancer InstituteCairo University, Cairo, Egypt. 3 Radiology department, National Cancer InstituteCairo University, Cairo, Egypt. 4 Radiation oncology physics, National Cancer InstituteCairo University, Cairo, Egypt Purpose/Objective: To assess the feasibility, safety and efficacy of a novel way of dose escalation with SBRT boost based on interim functional imaging (PET CT and DW MRI) in head and neck squamous cell carcinoma. Material/Methods: Proffered Paper 254
72 patients with locally advanced HNSCC were enrolled. Median age was 57 (range 20-77). 53 patients were males while 19 were females. Larynx was site of primary in 35 cases. 26 cases had nasopharynx primary. 6 had oropharynx primary while 5 had hypopharynx primaty. The median SUV max in initial PET/CT before treatment was 12.6, with a significant drop at interim analysis to the median SUV max of 5.3 (p <0.001). The median ADC level at initial assessment using fMRI was 0.7 (restricted diffusion). There was a significant rise in ADC at interim analysis (non- restricted) (p <0.001). 62.5% of the patients were good responders according to interim imaging. 2-year LRC was 69% for the whole population. 2-year LRC was 75% for good responders and 59% for poor responders. LRC was significantly worse in poor responders despite receiving dose escalation per protocol (p=0.041). There were no significant differences in LRC regarding all other factors. 2-year OS was 82% for good responders and 81% for poor responders (with no statistical difference). No grade 4- 5 toxicity was recorded. Rate of grade 3 toxicities was simiilar in both study arms. Conclusion: Functional imaging can feasibly guide selective dose escalation using SBRT. This adaptive protocol was associated with acceptable toxicity and promising locoregional control. This study lays groundwork for personalized RT but underscores the complexity of overcoming radioresistance. Multicenter studies are needed to validate these results and evaluate dose escalation in poor responders. Keywords: SBRT, HNSCC, Functional Adaptive planning
Patients with locally advanced HNSCC who are receiving radical concurrent chemoradiation were enrolled. Before radiotherapy planning, all patients had initial DW MRI and FDG PET CT. Then, another PET CT and DW MRI were done midtreatment during the
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