S344
Clinical - Breast
ESTRO 2026
scenarios revealed nuanced decision-making. For a 62- year-old hormone receptor positive/HER2 negative, cT1c, grade 2 patient, 38.9% would omit SLNB while 45.7% would still perform it. For a 73-year-old similar patient eligible for partial breast irradiation (PBI), 51.9% felt comfortable omitting SLNB regardless of radiotherapy type, while 16.4% only if treated with whole-breast radiotherapy.Regarding RT field design if SLNB is omitted, 67.3% would maintain standard tangents, 18.4% would base decisions on tumour features, and 14.3% reported they would use high tangents. When asked if whole-breast radiotherapy alone sufficiently compensates for SLNB omission regarding regional control, 38.8% indicated sometimes, 32.7% felt it would not compensate, and 28.6% were uncertain. For PBI in patients eligible for both PBI and SLNB omission, only 8.2% would recommend PBI in all cases, 59.2% would consider it only in certain cases (ex: 44.8% said concurrent prescription of endocrine therapy was a requirement), 18.4% would not consider PBI, and 14.3% would restrict to clinical trials. Conclusion: This survey reveals heterogeneity in Canadian radiation oncologist practices toward RT planning with SLNB omission, particularly regarding nodal target volume decisions. This highlights the need for guidelines to support de-escalation of SLNB omission and subsequent systemic and radiation therapy planning in Canada. References: Kang YJ, Han W, Park S, et al. Sentinel lymph node biopsy versus observation in clinically node-negative breast cancer (SOUND): Long-term follow-up of a randomised controlled trial. Lancet Oncol. 2024;25(5):558-567Reimer T, Stachs A, Veselinovic K, et al. Patient-reported outcomes for the Intergroup Sentinel Mamma study (INSEMA): a randomised trial with persistent impact of axillary surgery on arm and breast symptoms in patients with early breast cancer. Lancet. 2023;402(10397):1673-1685 Keywords: SLNB, radiotherapy, early-stage
Digital Poster Highlight 4923
Canadian physician attitudes toward sentinel lymph node biopsy omission in early-stage breast cancer: implications for radiotherapy planning Jean-Marc Bourque 1 , Arsene Manengue 2 , Pamela Brazeau-Porrello 3 , Ahmad Kaviani 3 , Kerianne Boulva 3 , Jeff Cao 4 , Tarek Hijal 5 , Michael Yassa 6 , Valerie Theberge 7 , Sharon McGee 8 , Erica Patocskai 3 , Anne- Marie Charpentier 1 , Ipshita Prakash 9 1 Radiation Oncology, Centre Hospitalier de l'Universite de Montreal, Montreal, Canada. 2 Biomedicine, University of Montreal, Montreal, Canada. 3 Surgery, University of Montreal, Montreal, Canada. 4 Radiation Oncology, University of Calgary, Calgary, Canada. 5 Oncology, McGill University, Montreal, Canada. 6 Radiation Oncology, University of Montreal, Montreal, Canada. 7 Radiation Oncology, Centre Hospitalier de l'Universite de Quebec, Quebec, Canada. 8 Medicine, University of Ottawa, Ottawa, Canada. 9 Surgery and Oncology, McGill University, Montreal, Canada
Purpose/Objective: Following the SOUND and INSEMA trials
demonstrating non-inferiority of sentinel lymph node biopsy (SLNB) omission in select early-stage breast cancer patients, there is a need to understand how this paradigm shift impacts radiation therapy (RT) planning. This survey examined Canadian physician attitudes toward SLNB omission, focusing on radiation oncologists' perspectives and practice patterns. Material/Methods: A 19-item anonymous survey was distributed to medical, surgical, and radiation oncologists across Canada (May-October 2025), assessing demographics, attitudes, and practice patterns regarding SLNB omission. Respondents represented all provinces, with majority from Ontario (26.3%), Quebec (26.3%), and
Alberta (11.5%). Practice settings included academic/teaching hospitals (71.7%) and
community/regional cancer centres (28.3%). Three items specifically addressed radiation oncology practice regarding nodal clinical target volume delineation and treatment planning with unknown nodal status. Results: Of 113 physicians (49 radiation oncologists, 56 surgical oncologists, 8 medical oncologists), 67.3% occasionally omitted SLNB per SOUND/INSEMA criteria, 15.9% routinely omitted, and 16.8% never omitted. Practice patterns varied significantly by experience: physicians with >21 years more frequently omitted SLNB (81.5%) versus 0-5 years (25.9%, p<0.001). Community/regional centre physicians were more likely to never omit SLNB (31.2%) versus academic centres (11.1%, p=0.021). No significant differences existed by region (p=0.37) or specialty (p=0.12).Clinical
Digital Poster 4928 Acute and late dysphagia following
hypofractionated locoregional breast irradiation Fatma Dhouib, Fatma Missaoui, Leila Farhat, Nejla Fourati, wicem Siala, Wafa Mnejja, Jamel Daoud oncology radiotherapy, Habib Bourguiba university hospital, SFAX, Tunisia Purpose/Objective: The side effects of hypofractionated radiotherapy for breast cancer, particularly dysphagia following locoregional radiotherapy (LRR), remain poorly
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