S2452
Physics - Radiomics, functional and biological imaging, and outcome prediction
ESTRO 2026
Conclusion: Our current NTCP model based on dose to IASN was not superior to one based on rectal dose. The model could possibly be improved by using both rectum and IASN parameters in a mixed model or using dosiomics. References: 1. Stelzner S, Böttner M, Kupsch J, Kneist W, Quirke P, West NP, Witzigmann H, Wedel T. Internal anal sphincter nerves–a macroanatomical and microscopic description of the extrinsic autonomic nerve supply of the internal anal sphincter. Colorectal Dis. 2018;20:O7- O16.2. Ishiyama G, Hinata N, Kinugasa Y, Murakami G, Fujimiya M. Nerves supplying the internal anal sphincter: an immunohistochemical study using donated elderly cadavers. Surg Radiol Anat. 2014;36:1033-42.3. Yeoh E, Botten R, Di Matteo A, Tippett M, Hutton J, Fraser R, Dinning PG, Wattchow D. Pudendal nerve injury impairs anorectal function and health related quality of life measures ≥ 2 years after 3D conformal radiotherapy for prostate cancer. Acta Oncol. 2018;57:456-64. Keywords: NTCP, prostate, gastrointestinal toxicity Proffered Paper 2805 Dose surface mapping of the pharyngeal mucosa relates feeding tube dependency during radiotherapy to subregions of interest Sven R.I. Meijer 1 , Markus Wendling 1 , Patricia A.H. Doornaert 2 , Frank J.P. Hoebers 3 , Bas Kreike 4 , Marije R. Vergeer 2 , Ellen M. Zwijnenburg 1 , Tim Dijkema 1 , Johannes H.A.M. Kaanders 1 , Sven van den Bosch 1 1 Radiation Oncology, Radboud University Medical Center, Nijmegen, Netherlands. 2 Radiation Oncology, Amsterdam UMC, Amsterdam, Netherlands. 3 Radiation Oncology (MAASTRO), Maastricht University, Maastricht, Netherlands. 4 Radiation Oncology, Radiotherapiegroep, Arnhem, Netherlands Purpose/Objective: The UPGRADE-RT randomized controlled trial (NCT02442375) compared the clinical benefit and safety of definitive accelerated radiotherapy with reduced versus standard elective dose to cervical lymph nodes in 300 patients with head and neck squamous cell carcinoma (SCC). Reduced elective dose was safe and resulted in significantly less tube feeding during treatment (acute dysphagia grade ≥ 3) compared to controls[1]. Dosimetric analysis demonstrated that pharyngeal mucosa mean dose was associated with mucositis grade ≥ 3 and subsequently with tube feeding[2]. Here we report the results of a spatial analysis of dose distribution to the pharyngeal mucosa in relation to tube feeding. Material/Methods: To contour the entire pharyngeal mucosal surface, the
Results: The included patients (n=694) mainly had baseline score 0-1 for all symptoms (91%). At year 1, 14% had late bowel symptoms. The rectum model showed the highest AUC (0.61) and its calibration slope and intercept showed the best agreement between predictions and outcomes, but was statistically not significantly better than the IASN and anus models (Fig. 2A-C). In Figure 2D, the IASN dose-response curves fitted separately for each fractionation scheme are similar to their combined data, suggesting the doses were appropriately combined using BED.
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