S254
Clinical - Breast
ESTRO 2026
Proffered Paper 1730
Digital Poster 1729 Interim result of the de-escalation of radiotherapy in patients with early breast cancer with involvement of one to three axillary lymph nodes. Irina Akulova 1 , Sergey Nikolaevitch Novikov 1 , Zhanna Bryantceva 1 , Petr Krivorotko 2 , Pavel Krzhivitskiy 3 , Sergey Kanaev 1 1 Radiotherapy, N.N. Petrov Cancer Institute, St Petersburg, Russian Federation. 2 Breast surgery, N.N. Petrov Cancer Institute, St Petersburg, Russian Federation. 3 Nuclear Mdeicine, N.N. Petrov Cancer Institute, St Petersburg, Russian Federation Purpose/Objective: To perform interim analysis of the de-escalation of radiotherapy in patients with early breast cancer with involvement of one to three axillary lymph nodes. Material/Methods: From February 2022 to October 2025 185 were included in this prospective randomized study. Inclusion criterias are as follows: T1-2N1 Luminal A BC, involvement of 1-2 sentinel or no more than 3 axillary LN after limited axillary dissection, age >44 y.o.All women underwent post-operative whole breast irradiation by high tangential fields with inclusion of axillary level I LNs: 15 fractions of 2.66Gy. Radiation portals were designed according to sentinel LN atlas (1). In the control group, postoperative radiotherapy was performed with irradiation of residual breast tissues, axillary level I-III and supraclavicular LN. Results: At the time of interim analysis, 76 patients had at least 2 years of follow-up (median time - 36 months; 24-56). A comparative analysis of locoregional control was performed in 65 patients from the study group and 11 women from the control group. The locoregional control rate, including in the ipsilateral supraclavicular region, was 100% in both groups. The two-year relapse-free survival was 98.5% in the study group and 100% in the control group [p>0.2]. 3 women in the study group developed generalization of BC with bone
Factors associated with arm swelling in patients undergoing surgery and radiotherapy for breast cancer within the FAST-Forward Trial Nodal Sub- study
Saranya Ravindra 1,2 , Fay H Cafferty 3 , Emma Harris 2 , Sarah Gulliford 4,5 , Elizabeth Miles 6 , Jaymini Patel 3 , Mark A Sydenham 3 , Sambhav Kumar 6 , Rushil Patel 6 , Sarah Mason 7 , Simeon Nill 7 , Alex Dunlop 7 , Adrian M Brunt 8,3 , Judith M Bliss 3 , Anna M Kirby 1,2 1 Department of Radiotherapy, The Royal Marsden NHS Foundation Trust, London, United Kingdom. 2 Division of Radiotherapy and Imaging, The Institute of Cancer Research, London, United Kingdom. 3 Clinical Trials and Statistics Unit, The Institute of Cancer Research, London, United Kingdom. 4 Department of Medical Physics & Biomedical Engineering, University College London, London, United Kingdom. 5 Department of Radiotherapy Physics, University College London Hospitals NHS Foundation Trust, London, United Kingdom. 6 National Radiotherapy Trials Quality Assurance Group, Mount Vernon Cancer Centre, London, United Kingdom. 7 The Joint Department of Physics, The Institute of Cancer Research and Royal Marsden Hospital, London, United Kingdom. 8 School of Medicine, University of Keele, Keele, United Kingdom Purpose/Objective: Arm lymphoedema, a recognised complication following locoregional therapy for breast cancer, compromises patients’ long-term quality-of-life. The FAST-Forward randomised nodal sub-study1 primary analysis showed non-inferiority for 5-year patient- reported arm/hand swelling (primary endpoint) following adjuvant axillary and breast/chest wall radiotherapy of 26Gy in 5 fractions (Fr) over 1 week compared to 40Gy in 15Fr over 3 weeks. This subsequent analysis investigated the association between patient, tumour and treatment factors and development of long-term arm swelling. Material/Methods: Data from all 469 FAST-Forward nodal sub-study patients randomised to adjuvant radiotherapy 40Gy/15Fr, 27Gy/5Fr and 26Gy/5Fr to breast/chest wall and axilla (any or all levels 1-4) were analysed. The 27Gy/5Fr group closed early based on 3-year normal tissue effects suggesting 26Gy/5Fr would be optimal. Patient-reported (EORTC-QLQ-BR23) and clinician- reported arm/shoulder outcomes had been collected prospectively. DICOM-RT data were collected prospectively and visible axillary seroma, ESTRO- defined axillary nodal levels 1-4 and the axillary-lateral thoracic vessel juncture were contoured
metastases. Conclusion:
Interim analysis indicate that in the study group omission of level II-III and supraclavicular LN irradiation after at least 2 year of follow-up does not decrease loco-regional control and does not increase the risk of BC recurrence in the supraclavicular region. References: 1. Novikov S.N., Krzhivitskii P.I., Melnik Y.S., et al. Atlas of sentinel lymph nodes in early breast cancer using singlephoton emission computed tomography: implication for lymphatic contouring. Radiat Oncol J. 2021; 39(1): 8-14. DOI: 10.3857/roj.2020.00871. Keywords: early breast cancer, rdiotherapy, deescalation
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