ESTRO 2025 - Abstract Book

S534

Clinical - Breast

ESTRO 2025

Material/Methods: WATCH is an ongoing cross-sectional cohort study of BC patients aged > 65 years, treated with radiotherapy (RT) at least five years before inclusion, without history of AF before RT. Cross-sectional screening for AF at inclusion is conducted by recording data from a Withings ScanWatch smartwatch for one month, confirmed by an ECG, and validated by a physician, following recommendations for opportunistic AF screening in individuals over 65. In addition to smartwatch AF screening, a transthoracic echocardiogram (TTE) is performed on all patients, providing comprehensive assessment of cardiac structures and functions. Retrospective data collection is based on patient's medical records providing information on the timing and risk factors for the occurrence of AF and other arrhythmias and cardiovascular disorders. Dosimetry for potentially critical sub-structures for the risk of AF (including cardiac chambers, sinoatrial node, atrioventricular node, coronary arteries, pulmonary veins) is based on manual delineations according to previously published atlas. Results: In November 2024, 45 patients were included. All patients were treated with VMAT. Mean age at inclusion was 73 years. Enrollment of patients and data collection are still ongoing and will be presented during ESTRO congress. Conclusion: In November 2024, 45 patients were included. All patients were treated with VMAT. Mean age at inclusion was 73 years. Enrollment of patients and data collection are still ongoing and will be presented during ESTRO congress. Mini-Oral Longitudinal changes in inflammatory biomarkers in early coronary artery calcification after breast cancer radiotherapy: the BACCARAT cohort study Médéa Locquet 1 , Gaelle Jimenez 2 , Jean Ferrières 3 , Matthieu Lapeyre 4 , Georges Tarlet 5 , Rodrigue Allodji 1 , Manoj Kumar Honaryar 1 , Jérémy Camilleri 2 , David Broggio 6 , Florent De Vathaire 1 , Fabien Milliat 5 , Sophie Jacob 7 1 Radiation Epidemiology, Gustave Roussy/Inserm, Villejuif, France. 2 Radiation Oncology (ORION), Clinique Pasteur, Toulouse, France. 3 Cardiology, Rangueil University Hospital, Toulouse, France. 4 Department of Radiology (GRX), Clinique Pasteur, Toulouse, France. 5 Radiobiology of Medical Exposure Laboratory, Institute for Radiation Protection and Nuclear Safety, Fontenay-aux-Roses, France. 6 Dosimetry Laboratory, Institute for Radiation Protection and Nuclear Safety, Fontenay-aux-Roses, France. 7 Laboratory of Epidemiology (LEPID), Institute for Radiation Protection and Nuclear Safety, Fontenay-aux-Roses, France Purpose/Objective: Radiotherapy (RT) for breast cancer (BC) is known to increase cardiovascular complications, including atherosclerosis, many years after treatment. Additionally, inflammation is a crucial process linking cardiovascular disease risk factors. This study aimed then to assess the association between inflammatory biomarkers, cardiac radiation dose, and early coronary artery calcification (CAC) score progression among BC women treated by RT. Material/Methods: The BACCARAT prospective cohort study included BC women treated with RT without chemotherapy. Inflammatory biomarkers (C-reactive protein (CRP), fibrinogen, tumor necrosis factor-α, and interleukin-6) were measured before RT (V0), after RT (V), and at 6 (V6) and 24 (V24) months post-RT. CAC score was assessed using computed tomography scans before RT and 24 months post-RT. Multivariate logistic regression models assessed potential associations between inflammatory biomarker changes, cardiac radiation dose, and CAC score progression. Keywords: Breast cancer, atrial fibrillation, smartwach 2529