S263
Clinical - Breast
ESTRO 2026
1 Oncology, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom. 2 Palliative Care, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom. 3 Oncology and Haematology, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom Purpose/Objective: Breast cancer is the most common cancer amongst women, with an incidence of over 2 million cases globally(1). Prognosis in metastatic disease varies according to histological subtype and hormone status, with the spine being a common site of metastasis. Appropriate management of vertebral metastases is therefore essential as some patients can live for several years. According to NICE guidance NG234, radiotherapy is recommended for symptomatic spinal disease or metastatic spinal cord compression (MSCC), with an 8Gy single fraction being the preferred treatment schedule(2). We evaluated the radiotherapy management and need for re-irradiation of this patient population at Oxford University Hospitals NHS Foundation Trust. Material/Methods: Using electronic patient records and our local radiotherapy database, we conducted a retrospective analysis of patients who received palliative radiotherapy for spinal metastases secondary to breast cancer between January 2020 and December 2022. Statistical analysis was performed using Microsoft Excel and appropriate statistical tests. Results: A total of 159 breast cancer patients received 170 courses of palliative radiotherapy across 165 spinal sites. 51% were treated electively and 49% received emergency radiotherapy for MSCC or impending MSCC. Compared with the wider cohort of all cancer patients receiving palliative spinal radiotherapy, there was a statistically significant trend towards proactive rather than emergency treatment in our breast cancer cohort.58% of patients were oestrogen receptor (ER) positive/HER2 receptor (HER2R) negative, 16% were HER2R positive, 5% were triple-negative, and 21% had unknown receptor status. Re-irradiation occurred in 31 cases (18.8%): 22 ER positive/HER2R negative, 5 HER2R positive, no triple-negative, and 4 unknown cases. Among ER positive/HER2R negative cases, 8Gy single fraction was the most common initial schedule, with re-irradiation equally as likely to be delivered as either another 8Gy single fraction or 20Gy in 5 fractions. Due to small numbers, no firm conclusions were drawn for HER2R positive disease. Across the breast cancer cohort, 9% of patients died within 30 days of radiotherapy, with a mean post-treatment survival of 396 days. Conclusion: Overall, our data indicate that ER positive/HER2R
negative patients are more likely to require re- irradiation than other histological subtypes, likely reflecting improved prognosis and survival. There needs to be careful consideration of dose fractionation for this group as there is a 2.6-fold reduction in re-irradiation of patients who receive 20Gy in 5 fractions compared to an 8Gy single fraction(3). No triple-negative patients required re- irradiation, supporting the continued use of an 8Gy single fraction in this subgroup. References: 1. World Cancer Research Fund. Breast cancer statistics [Internet]. World Cancer Research Fund International; 2022 [cited 2025 Oct 29]. Available from: https://www.wcrf.org/preventing-cancer/cancer- statistics/breast-cancer-statistics/2.National Institute for Health and Care Excellence (NICE). Spinal metastases and metastatic spinal cord compression: NICE guideline [NG234] [Internet]. NICE; 2023 [cited 2025 Oct 29]. Available from: https://www.nice.org.uk/guidance/ng234/chapter/Rec ommendations#radiotherapy3. Chow E, Zeng L, Salvo N, Dennis K, Tsao M, Lutz S. Update on the systematic review of palliative radiotherapy trials for bone metastases. Clin Oncol (R Coll Radiol). 2012 Mar;24(2):112-24. doi: 10.1016/j.clon.2011.11.004. Keywords: Spinal metastasis, palliative radiotherapy Surgery de-escalation in patients with pathologic complete response after neoadjuvant therapy: comparison with matched retrospective groups. Zhanna Bryantceva 1 , Sergey N Novikov 1 , Irina Akulova 1 , Petr Krivorotko 2 , Nikolay Amirov 2 , 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 Purpose/Objective: There is a current perspective that in breast cancer (BC) patients who achieve a pathological complete response (pCR) after neoadjuvant systemic therapy (NST), performing surgery serves a diagnostic rather than therapeutic purpose and does not impact long- term treatment outcomes. This work presents a retrospective analysis of treatment outcomes in patients with triple-negative and HER2-positive BC who achieved pCR after NST, based on the type of invasive breast intervention performed, including patients who underwent only vacuum-assisted biopsy (VAB) without subsequent breast surgery. Material/Methods: The study included patients with unifocal invasive HER2-positive and triple-negative BC (cT1–2N0–1M0) Digital Poster Highlight 2009
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