ESTRO 2024 - Abstract Book

S670

Clinical - Breast

ESTRO 2024

On the contralateral side, the VMAT plans gave the breast a median (IQR) mean dose of 4.6 (3.6-5.7) Gy and V15Gy of 3.8 (2.0-7.5) %. The lung received median 2.3 (1.9-2.9) Gy in mean dose and a V5Gy of 6.5 (2.1-12.7) %.

Conclusion:

VMAT has shown to be an attractive planning option for breast cancer patients with challenging anatomy: It ensures excellent target coverage while maintaining dose to heart and ipsilateral lung at levels comparable to those for 3DCRT. This avoids the need for compromising target coverage, but comes at the cost of an increased low dose bath to all OAR. For ipsilateral OAR this represents a tradeoff between high dose and low dose volumes, while contralateral OAR receive, while still low, significantly increased doses. The increased low dose bath has caused concern for the risk of inducing secondary cancers, especially in the contralateral OARs. Patients treated with VMAT should be followed long-term to evaluate this risk and until these data are available the clinician has a responsibility to pay special attention to keep the low dose volume as small as possible.

Keywords: VMAT, challenging anatomies,

2753

Poster Discussion

A nomogram for predicting local recurrence risk in breast cancer after intraoperative radiotherapy

DAMARIS PATRICIA ROJAS 1 , MARIA CRISTINA LEONARDI 1 , SAMUELE FRASSONI 2 , VINCENZO BAGNARDI 2 , PATRICK MAISONNEUVE 3 , CRISTIANA FODOR 1 , GIUDITTA MAZZEI 1,4 , FRANCESCA BRAGA 1,4 , SAMANTHA DICUONZO 1 , MARIANNA ALESSANDRA GERARDI 1 , MARIA ALESSIA ZERELLA 1 , ANNA MORRA 1 , PAOLO VERONESI 5 , VIVIANA ENRICA GALIMBERTI 5 , MATTIA INTRA 5 , FEDERICA CATTANI 1 , MATTIA ZAFFARONI 1 , ANDRIANA KOULOURA 5 , ROBERTO ORECCHIA 6 , BARBARA ALICJA JERECZEK-FOSSA 1,4 1 European Institute of Oncology, Radiotherapy Division, MILAN, Italy. 2 University of Milan-Bicocca, Department of Statistics and Quantitative Methods, MILAN, Italy. 3 European Institute of Oncology, Division of Epidemiology and Biostatistics, MILAN, Italy. 4 University of Milan, Department of Oncology and Hemato-oncology, MILAN, Italy. 5 European Institute of Oncology, Division of breast surgery, MILAN, Italy. 6 European Institute of Oncology, Scientific Directorate, MILAN, Italy

Purpose/Objective:

This study aimed to identify a useful tool for predicting local recurrence (LR) in breast cancer (BC) patients treated with intraoperative radiotherapy with electrons (IOERT) as the sole treatment

Material/Methods: