ESTRO 2025 - Abstract Book

S448

Clinical - Breast

ESTRO 2025

Conclusion: 5-year patient-reported arm/shoulder symptoms were similar with 26Gy/5Fr and 40Gy/15Fr suggesting 26Gy/5Fr hypofractionation is safe for breast cancer patients requiring adjuvant axillary radiotherapy.

Keywords: Hypofractionation, nodal, patient-reported

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Proffered Paper Longitudinal ADC Imaging for Treatment Response Prediction in Breast Cancer: Prognostic Radiomic Features and Related Functional Pathways Xinyu Zhang, Xinzhi Teng, Jiang Zhang, Qingpei Lai, Ge Ren, Jing Cai Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong, China Purpose/Objective: This study aims to identify the radiomic features and their changes extracted from longitudinal apparent diffusion coefficient (ADC) images during neoadjuvant chemotherapy (NAC) that can enhance the prediction of breast cancer pathological complete response (pCR) and investigate their correlations with functional pathways of breast tumors. Material/Methods: A total of 385 patients in ACRIN6698/I-SPY2 Breast DWI dataset were included and organized into three cohorts: feature discovery, prognostic analysis, and radiogenomics [1]. In feature discovery cohort having pre-treatment (T0) ADC images, radiomic features were extracted from T0 ADC images and evaluated for perturbation and test-retest intra-class correlation coefficients, remaining those with at least moderate reliability, after which K-means clustering