ESTRO 2025 - Abstract Book

S3938

Radiobiology - Normal tissue radiobiology

ESTRO 2025

1 Department of Radiation Biology, Oslo University Hospital, Oslo, Norway. 2 Institute of Oral Biology, University of Oslo, Oslo, Norway. 3 Department of Physics, University of Oslo, Oslo, Norway. 4 Department of Pathology, Oslo University Hospital, Oslo, Norway Purpose/Objective: Radiotherapy of head and neck cancer may cause detrimental late side effects such as fibrosis and hyposalivation. Our aim was to investigate late radiation-induced cellular and molecular changes of the salivary glands after fractionated irradiation to the head and neck in a murine model. Material/Methods: 12-week-old female C57BL/6J mice were irradiated with X-rays to a total dose of 66 Gy, given in 10 fractions over 5 days. The radiation field covered the oral cavity and major salivary glands. Salivary gland function was assessed by collecting saliva at baseline and at various time points after irradiation. The submandibular (SMG), sublingual (SLG), and parotid glands (PG) were dissected at day 105. Using different staining techniques, morphological, cellular, and molecular changes were investigated in the salivary glands. Results: Saliva production was significantly reduced in irradiated compared to control mice at day 35, 80, and 105. We observed a significant decrease in total gland area and a significant increase in fibrotic area in irradiated compared to control SMG at day 105. Atrophy of acinar cells was observed in all irradiated SMG and SLG. Increased amount of chronic inflammatory cells, increased cell proliferation and altered expression of apoptotic markers were found in atrophic areas of irradiated glands. Conclusion: We demonstrate that fractionated irradiation in a murine model induces hyposalivation caused by focal acinar atrophy and their replacement by fibrotic tissue. Acinar and ductal cells in irradiated salivary glands show increased cell proliferation and altered expression of apoptotic markers, proposing an attempt to overcome or withstand tissue damage caused by irradiation. This suggests a potential for regeneration of salivary glands after radiation therapy. Proffered Paper Predicting radiotherapy-induced erectile dysfunction in prostate cancer patients using a germline genetic neural network model Jung Hun Oh 1 , Sarah Kerns 2 , William Hall 2 , Sangkyu Lee 1 , Barry S. Rosenstein 3 , Joseph O. Deasy 1 1 Medical Physics, Memorial Sloan Kettering Cancer Center, New York, USA. 2 Radiation Oncology, Medical College of Wisconsin, Milwaukee, USA. 3 Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, USA Purpose/Objective: Radiation-induced erectile dysfunction (ED) is a common toxicity observed in prostate cancer patients undergoing radiotherapy. Several studies have investigated associations between the risk of radiation-induced ED and single nucleotide polymorphisms (SNPs) through genome-wide association studies (GWAS). In this study, we tested the capability of a biologically Interpretable neural network model to predict radiation-induced ED using GWAS data. Material/Methods: Germline DNA from blood samples of 668 prostate cancer patients was genotyped in the GenePARE study, consisting of two-phase GWAS [1-2]. Imputation was performed for each phase cohort utilizing the Michigan Keywords: fractionation, late effects, salivary glands 2986