ESTRO 2025 - Abstract Book

S555

Clinical - Breast

ESTRO 2025

From MLR, in ACUG2+/EDMG2+/FTELG2+ none of the combinations of HU-Histogram parameters increased the predictive power of CTV volume, whose ULR results are reported in Table-2a. Concerning LIPNEC, even if CTV Volume resulted to be predictive (p=0.0464), a model constituted by the HU-Mean and the count of the maximum HU value of the histogram (p=0.0054) was trained (AUC= 0.57) and confirmed in validation cohort (AUC=0.58). See Table-2b.

Conclusion: The association between parameters extracted from CTV HU-Histograms and relevant toxicities after whole breast Radiotherapy is weak compared to CTV volume, excepting for LIPNEC. In particular, higher the HU-mean and lower is the risk of LIPNEC.

Keywords: Breast, toxicity, biomarkers

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Digital Poster Advanced delivery techniques reduce the incidence of oedema after post-operative whole breast Radiotherapy Monica Maria Vincenzi 1 , Roberta Castriconi 1 , Anna Chiara 2 , Chiara Lucrezia Deantoni 2 , Paola Mangili 1 , Martina Mori 1 , Marcella Pasetti 2 , Miriam Torrisi 2 , Roberta Tummineri 2 , Antonella Del Vecchio 1 , Nadia Gisella Di Muzio 2,3 , Claudio Fiorino 1 , Andrei Fodor 2 1 Medical Physics, IRCCS San Raffaele Scientific Institute, Milan, Italy. 2 Radiation Oncology, IRCCS San Raffaele Scientific Institute, Milan, Italy. 3 Medicine, Vita-Salute San Raffaele University, Milan, Italy Purpose/Objective: Oedema is a quite common side effect of breast radiotherapy and may significantly affect patients' quality of life in both short and long term (1,2,3). The aim of current study is to assess the impact of the introduction of advanced delivery techniques (AT), gradually replacing the conventional tangential field (3d-CRT) approach.