S2622
Radiobiology - Translational radiobiology
ESTRO 2026
pneumonitis. The 3-years overall survival was 46%,. There was no significant difference in overall survival for the patients treated with concurrent or sequential chemoradiotherapy. Conclusion: The largest NTCP benefit for protons compared to photons was due to a lower dose to the heart (mean: 7.8%). We observed a 3-years overall survival of 46%. As 66% of the patients had a NTCP difference of ≥ 5% based on the dose to the heart, this patient group can be used for future randomized studies. References: 1. Patient selection for proton therapy in lung cancer: Nationwide external validation and model update of a prognostic model for 2-year mortality including mean heart dose. van Loon J, Wijsman R, Boersma L, Langendijk JA, Krol S, Schuit E; national platform for proton therapy for lung cancer. Radiother Oncol. 2025 Nov 3:111257 Keywords: Proton therapy, NTCP, lung cancer
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Outcome and dose characteristics after model- based proton therapy for stage III Non-Small Cell Lung Cancer to guide future studies Joost Jan Nuyttens 1,2 , Christa van Doorn 3,2 , Stefan Hutschemaekers 4,2 , Anne Lisa Wolf 2 , Michiel Kroesen 2,1 , Rutger Bartels 2,1 1 Department of Radiotherapy, Erasmus MC Cancer Institute, Rotterdam, Netherlands. 2 Department of Radiotherapy, HollandPTC, Delft, Netherlands. 3 Department of Radiation Oncology, Leiden University Medical Center, Leiden, Netherlands. 4 Department of Radiation Oncology, Haaglanden MC, The Hague, Netherlands Purpose/Objective: The goal of this prospective study was to evaluate non- small cell lung cancer (NSCLC) patients treated protons with a focus on the dose to organs of interest and Normal Tissue Complication Probabilities (NTCP) compared to photons in order to guide future studies. Material/Methods: In the Netherlands, patient selection for proton therapy for lung cancer is model-based, involving a plan comparison between photon and proton therapy. Three NTCP models are used in lung cancer patients, predicting 2-year treatment related mortality (based on mean heart dose (MHD))1, acute grade 2 dysphagia (based on mean esophageal dose (MED)) and grade 2 dyspnea (based on mean lung dose (MLD)). The difference in the NTCP values ( Δ ) required for proton therapy selection are recorded in a national indication protocol: Δ NTCP 2% for 2-year mortality, 10% for dysphagia or dyspnea. The patients were treated with concomitant chemoradiotherapy to 60 Gy in 30 fractions or sequential chemoradiotherapy to 55- 66 Gy in 20-24 fractions. All patients signed an informed consent. Results: A total of 76 patients with NSCLC were prospectively enrolled between 04/2021 and the end of 12/2024, of which 69 had Stage III disease and 7 stage IV (solitary metastasis). The MHD, MED and MLD were on average 6.3 Gy, 1.8 Gy and 2.0 Gy lower with protons compared to the photons. This resulted in a mean Δ NTCP of 7.8% for 2-year mortality, 2.9% for G2 dysphagia and 3.5% for G2 dyspnea. A total of 96% of the treated patients were eligible for proton therapy based on the 2-year mortality model, involving the MHD. A Δ NTCP ≥ 5% was seen in 66% of the patients, a Δ NTCP ≥ 10% was seen in 29% of patients. Only 16% and 20% of the patients met the Δ NTCP selection criteria for dysphagia or dyspnea, respectively. The severe acute and late toxicity was low: 2 patients required a feeding tube during or shortly after the radiotherapy (G3 dysphagia). One patient suffered G5
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Boosting radiotherapy efficacy and shaping the immune microenvironment in colorectal cancer with onion-like carbon nanophotothermal therapy. Ruiping Guo, Zhuhui Yuan, Hao Wang Radiation Oncology, Peking University Third Hospital, Beijing, China
Proffered Paper 3737 Sparing Elective Nodes during Head - and - Neck Cancer Radiotherapy Mitigates Lymphocyte Exposure: Biodosimetric Findings from a Randomized Trial Justus Kaufmann 1 , Sophia Drabke 1 , Ahmed Salah 1,2 , Nina Gercek 1 , Stephanie Goeller 1 , Laura Oebel 1 , Heinz Schmidberger 1 , Sebastian Zahnreich 1 1 Radiation Oncology and Radiation Therapy, University Medical Center Mainz, Mainz, Germany. 2 Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Center Mainz, Mainz, Germany Purpose/Objective: Radiotherapy (RT) for head-and-neck squamous-cell carcinoma (HNSCC) can cause lymphopenia,
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