ESTRO 2024 - Abstract Book

S511

Clinical - Breast

ESTRO 2024

(G1) fat necrosis occurred in 8 (11.2%) patients. Cosmetic outcome was excellent in 44 (61.9%), good in 24 (33.9%), and fair in 3 (4.2%) patients. No grade 1-2 acute or late side-effect was detected

Conclusion:

SAPBI with CK is a feasible technique for the administration of external beam APBI following BCS for the treatment of low-risk, early-stage invasive breast carcinoma. Our findings are promising, CK-SAPBI delivered with four daily fractions is well tolerated by the patients, with excellent clinical result.

Keywords: Stereotactic, partial breast irradiation,

761

Proffered Paper

Quality assurance of internal mammary node irradiation 2007-14: The DBCG IMN2 study

Anders W. Mølby Nielsen 1 , Emma S. Buhl 2,3 , Lasse Refsgaard 1,2 , Mette S. Thomsen 4 , Karen Andersen 5 , Ingelise Jensen 6 , Martin Berg 7 , Ebbe L. Lorenzen 8 , Lise B. J. Thorsen 1,9 , Jens Overgaard 1 , Stine S. Korreman 2,3 , Birgitte V. Offersen 1,2,9 1 Aarhus University Hospital, Department of Experimental Clinical Oncology, Aarhus, Denmark. 2 Aarhus University Hospital, Danish Center for Particle Therapy, Aarhus, Denmark. 3 Aarhus University, Department of Clinical Medicine, Aarhus, Denmark. 4 Aarhus University Hospital, Department of Medical Physics, Aarhus, Denmark. 5 Copenhagen University Hospital - Herlev and Gentofte, Department of Oncology, Copenhagen, Denmark. 6 Aalborg University Hospital, Department of Medical Physics, Aalborg, Denmark. 7 Vejle Hospital, University Hospital of Southern Denmark, Department of Medical Physics, Vejle, Denmark. 8 Odense University Hospital, Department of Oncology, Odense, Denmark. 9 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark

Purpose/Objective:

The Danish Breast Cancer Group (DBCG) IMN2 study investigates the gain from internal mammary node irradiation (IMNI) in 4,544 node-positive breast cancer patients treated 2007-14. IMNI quality is highly dependent on target volume delineations. In the DBCG IMN2, target volume delineations were based on bony landmarks and included intercostal space (IC) 1-4. In contrast, the ESTRO consensus guideline 1,2 is vessel-based and includes often only IC1-3 but extends more cranial. Therefore, our objective is two-fold. First, to compare internal mammary node (IMN) doses between the original delineations and ESTRO delineations. Second, to compare IMN and organs at risk (OAR) doses in left and right-sided breast cancer patients.

Material/Methods: