S548
Clinical – Head & neck
ESTRO 2026
Maider Campo Vargas 1 , Intza Uranga Aizpurua 1 , Eva Maria Saenz de Urturu Albisu 1 , Belén De Paula Carranza 1 , Elena Guimón Olaizola 1 , Arrate Querejeta Ayerra 1 1 Radiation Oncology, Osakidetza, San Sebastian, Spain. 2 Radiation Oncology, Osakidetza, Vitoria, Spain Purpose/Objective: To analyze the differential evolution of the adipose and muscle compartments in patients undergoing radiotherapy for head and neck tumors, with the aim of identifying clinical variables that may influence anatomical changes during treatment and predicting which patients could benefit from replanning. Material/Methods: Between May 2024 and May 2025, a single-institution observational study with consecutive inclusion and retrospective data collection was conducted in those patients with head and neck squamous cell carcinomas treated with exclusive radical radiotherapy or concomitant chemoradiotherapy. Patients with non-squamous histology, salivary gland tumors, prior surgery, stage I–II disease, disseminated disease or palliative treatment were excluded.Adipose and cervical muscle compartments were contoured automatically using Hounsfield unit ranges (muscle -29 to +150, fat -190 to -30) on a single 2 mm slice at the inferior border of C3, on the weekly CBCT. Manual adjustments were then applied to weekly CBCT over the seven-week treatment period to ensure anatomical accuracy (1).
T6, and T9). The complete dataset was available for correlation at T6, corresponding to the expected peak of mucositis severity. These patients represent a homogeneous cohort undergoing concomitant chemoradiotherapy with standard supportive care. At T6, OMAS and CTCAE were strongly correlated (r = - 0.07), indicating substantial overlap in grading mucosal injury. MDADI showed a moderate inverse correlation with CTCAE (r = -0.17) and a weaker negative correlation with OMAS (r = -0.36). These patterns suggest that while OMAS and CTCAE capture a common clinical dimension of mucositis, MDADI primarily reflects patient - centred functional impact rather than lesion severity. Scatter visualisation did not indicate outlier - driven effects. Conclusion: OMAS and CTCAE largely overlap in quantifying mucosal injury at the peak of CRT - related toxicity, whereas MDADI contributes complementary information on swallowing function and quality of life. Integrating all three scales yields a multidimensional profile of mucositis; if burden reduction is required, coupling a lesion/grade metric (OMAS or CTCAE) with MDADI may preserve clinical granularity with fewer measures. References: 1.Freites-Martinez A et al Using the Common Terminology Criteria for Adverse Events (CTCAE - Version 5.0) to Evaluate the Severity of Adverse Events of Anticancer Therapies. 2021 Jan;112(1):90-92.doi: 10.1016/j.ad.2019.05.0092.Minhas S et al Assessment and prevalence of concomitant chemo-radiotherapy- induced oral mucositis in patients with oral squamous cell carcinoma. Turk J Med Sci. 2021 Apr 30;51(2):675- 684. doi: 10.3906/sag-2007-1313.Chen AY et al. The development and validation of a dysphagia-specific quality-of-life questionnaire for patients with head and neck cancer: the M. D. Anderson dysphagia inventory. Arch Otolaryngol Head Neck Surg. 2001 Jul;127(7):870- 6 Keywords: mucositis,OMAS, MDADI, CTCAE, chemoradiotherapy Changes in muscular and adipose compartments during radiotherapy for head and neck cancer Ainhoa Díez Arancibia 1 , Carlos Vicente Blanco Garcia 1 , Sara Palacios Moreno 1 , Xabier Gurutzeaga Peleato 1 , Ane Otaegi Aristi 2 , Ane Dehesa Urkia 1 , Sebastian Luévano Garcia 1 , June Ugarte Aguirre 1 , Oihane Alustiza Calvillo 1 , Beraldo Enrique Martínez Sebastia 1 , Ane Mugica Uranga 1 , Usoa Iceta Oleaga 1 , Amaia Sanchez Martin 1 , Leyre González Vallejo 1 , Alai Goñi Ramírez 1 , Daniel Alberto Roura 1 , Julian Mínguez Manrique 1 , Maria Pagola Divasson 1 , Mikel Eguiguren Bastida 1 , Digital Poster 782
Results: Twenty-five patients were included (72% men (18), 28% women (7)), with a median age of 68, and 64% of patients were over 65 years old. Sixty percent of tumors were stage III and 40%, stage IV. 28% of the tumors were located in the oral cavity and
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