ESTRO 2025 - Abstract Book

S413

Clinical - Biomarkers

ESTRO 2025

dose-volume histogram (DVH) parameters were collected for each patient. Multivariate logistic regression analysis was conducted to evaluate the weights of the influencing factors.

Results: The main radiotherapy-related adverse reactions in patients with locally advanced rectal cancer undergoing TNT were hematochezia, diarrhea, abdominal pain, colitis, and a sensation of anal heaviness. At initial diagnosis, factors such as imaging N stage, extramural vascular invasion (EMVI), circumferential tumor involvement, lesion length, differences in red blood cell counts before and after TNT, differences in platelet counts before and after TNT, decrease in albumin levels before and after TNT, neutrophil-to-lymphocyte ratio (NLR) after TNT, positive fecal occult blood tests during TNT, tumor regression grade (TRG), Ki-67 expression, positive vascular tumor thrombus, gross tumor volume (GTV), hematochezia, sensation of anal heaviness, and Disease Activity Index (DAI) scores were significantly correlated with the occurrence of SARE (all P < 0.05). Multivariate logistic regression analysis revealed that the decrease in albumin levels before and after neoadjuvant therapy (OR = 11.223, 95% CI : 1.631-77.228, P = 0.014), sensation of anal heaviness (OR = 7.683, 95% CI : 1.105-53.410, P = 0.039), and DAI scores (OR = 15.149, 95% CI : 1.092-210.246, P = 0.043) were independent predictors for the occurrence of SARE. Conclusion: The reduction in albumin levels before and after TNT, the presence of a sensation of anal heaviness, and the DAI score can accurately, conveniently, and cost-effectively predict SARE. These factors are important clinical nutritional indicators for assessing the severity of RE. References: [1] Moraitis I, Guiu J, Rubert J. Gut microbiota controlling radiation-induced enteritis and intestinal regeneration. Trends Endocrinol Metab. 2023;34(8):489-501. [2] Li H, Zhao S, Jiang M, et al. Biomodified Extracellular Vesicles Remodel the Intestinal Microenvironment to Overcome Radiation Enteritis. ACS Nano. 2023;17(14):14079-14098. [3] Yang XF, Zheng MY,et al. Quality evaluation of guidelines for the diagnosis and treatment of radiation enteritis. Radiat Oncol. 2023;18(1):14. [4] Wang J, Hu G. Nomogram to Predict Radiation Enteritis in Cervical Squamous Cell Carcinoma. Cancer Manag Res. 2022;14:3303-3311. Keywords: radiation enteritis, nutritional indicators, LARC Mini-Oral Liquid biopsy-based molecular characterization of oligometastatic state in prostate cancer: the RADIOSA trial (NCT03940235) biology task Mattia Zaffaroni 1 , Maria Giulia Vincini 1 , Giulia Marvaso 1,2 , Chiara Lorubbio 1 , Konstantinos Venetis 3 , Giulia Cursano 3 , Cristiana Iuliana Fodor 1 , Francesco Alessandro Mistretta 4,2 , Stefano Luzzago 4,2 , Gennaro Musi 4,2 , Ottavio De Cobelli 4,2 , Giuseppe Petralia 5,2 , Gabriella Pravettoni 6,2 , Nicola Fusco 3,2 , Piet Ost 7 , David Palma 8 , Chad Tang 9 , Barbara Alicja Jereczek-Fossa 1,2 1 Division of Radiation Oncology, European Institute of Oncology IRCCS, Milan, Italy. 2 Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy. 3 Division of Pathology, European Institute of Oncology IRCCS, Milan, Italy. 4 Division of Urology, European Institute of Oncology IRCCS, Milan, Italy. 5 Division of Radiology, European Institute of Oncology IRCCS, Milan, Italy. 6 Division of Applied Research for Cognitive and Psychological Sciences, European Institute of Oncology IRCCS, Milan, Italy. 7 Division of Radiation Oncology, Iridium Network, Wilrijk, Belgium. 8 Division of Radiation Oncology, Western University and London Health Sciences Centre, London, Ontario, Canada. 9 Department of Genitourinary Radiation Oncology, MD Anderson Cancer Center, Houston, TX, USA 1872