ESTRO 2025 - Abstract Book

S597

Clinical - Breast

ESTRO 2025

approach offers potential benefits, including the avoidance of additional surgery, reduce delays in systemic treatment, and improved aesthetic and psychological outcomes. Further validation thoungh larger cohorts of prospective, studies is warranted to confirm these findings and explore additional therapeutic options.

Keywords: breast cancer, oncoplastic surgery

3750

Digital Poster Long-term follow-up results of helical tomotherapy for non-metastatic breast cancer: single center experience Abdelkarim Uakkas, Jihane Bouziane, Pierre Loap, Youlia Kirova Radiation oncology, Institute Curie, Paris, France Purpose/Objective: The aim of our study is to explore the application of helical tomotherapy in the treatment of breast cancer, assessing its efficacy, safety, and role in the current therapeutic framework by analysing the clinical data and survival outcomes of our cohort of patients. Material/Methods: This single-center retrospective study was conducted at the department of radiation oncology of the Institute Curie (Paris, France) and included 179 patients treated with helical tomotherapy for breast cancer beetween 2009-2015. Overall survival and progression free survival curves were plotted with Kaplan-Meier method. We also analysed the overall survival and progression-free survival data by molecular subgroups. Acute and long-term toxicity including skin, cardiac and pulmonary complications were also evaluated. Results: 179 patients (15 of whom had bilateral cancer) were treated between 2009 and 2015 with helical tomotherapy for non-metastatic breast cancer. The median age of the patients was 53 years. Of these, 189 were treated for non specific invasive carcinoma, while 5 patients were treated for carcinoma in situ. 85.1% of patients had lymph node irradiation associated with breast or chest wall irradiation. 152 of the 163 irradiated breasts received a boost at the lumpectomy bed. The median duration of treatment was 46 days. After a median follow-up of 10 years, there were 9 local recurrences, 2 regional lymph node recurrences and 29 patients had metastatic progression. Only 18 patients died at the end of the study, of whom 7 were cancer-related. At 10 years, local recurrence-free survival was 95.3%, locoregional recurrence-free survival was 94.5%, metastasis free survival was 82.9%, specific survival was 94.3%, and overall survival was 88%. The occurrence of local, regional or distant recurrence correlated neither with HR or HER2 status, nor with grade, nor with the presence of emboli. In terms of molecular subgroups, recurrence-free survival was 86.3%, 90.9% and 76.7% respectively for the triple negative, HER+ and RH+/HER2- subgroups. In terms of acute skin toxicities, 96 patients presented grade 1 radioepithelitis, 72 grade 2 and 6 grade 3. 40 patients had late skin toxicity at last follow-up. No grade 3 or higher acute or late toxicity and no radiation-induced late pulmonary or cardiac toxicity was reported. Conclusion: This analysis summarises the clinical data and survival results associated with helical tomotherapy in patients with non-metastatic breast cancer, highlighting low recurrence rates and good treatment tolerance, confirming the relevance of this technique in specific indications.

Keywords: helical tomotherapy, breast cancer