ESTRO 2025 - Abstract Book

S518

Clinical - Breast

ESTRO 2025

Material/Methods: This retrospective study analyzed 292 breast cancer patients who received immediate reconstruction with implants and adjuvant radiotherapy (2010–2022). Sociodemographic factors, comorbidities, and treatment modalities were examined. Dosimetric analysis focused on the volume of the prosthesis and a 1 cm ring contour around the implant within the Clinical Target Volume (CTV). Statistical significance was set at p < 0.05, with Pearson's chi-square and Fisher’s exact tests used for analysis. Results: Patients had a median age of 43 years and a median follow-up of 49 months. All patients received adjuvant radiotherapy at a conventional dose of 50 Gy in 25 fractions. The overall implant loss rate was 13%, with no significant differences between 3D (15%), IMRT (11%), and VMAT (9%) techniques (p = 0.4). In multivariate analysis, postoperative complications were associated with a higher risk of implant loss (OR 2.46, p = 0.012). Seroma was significantly linked to implant loss (OR 2.71, p = 0.042), and sub-pectoral implant placement was associated with lower loss rates compared to pre-pectoral placement (12% vs. 26%, p = 0.031). Dosimetrically, exceeding 108% of the prescribed dose in the 1 cm ring contour was predictive of implant loss (p = 0.004). The ROC curve established a 4.57 cc threshold for V108%, with sensitivity of 0.7 and specificity of 0.57. Conclusion: The study found no significant difference in implant loss rates between 3D, IMRT, and VMAT techniques. However, postoperative complications and dosimetric factors, such as exceeding 108% of the dose around the prosthesis, were associated with increased risk. Maintaining V108% below 4.57 cc could reduce implant loss. References: Dicuonzo S, Leonardi MC, Radice D, et al. Long-Term Results and Reconstruction Failure in Patients Receiving Postmastectomy Radiation Therapy with a Temporary Expander or Permanent Implant in Place. Plast Reconstr Surg. 2020;145(2):317-327 Clarke M, Collins R, Darby S, et al. Effects of radiotherapy and of differences in the extent of surgery for early breast cancer on local recurrence and 15-year survival: an overview of the randomised trials. Lancet. 2005;366(9503):2087 2106 Naoum GE, Salama L, Niemierko A, et al. Single Stage Direct-to-Implant Breast Reconstruction Has Lower Complication Rates Than Tissue Expander and Implant and Comparable Rates to Autologous Reconstruction in Patients Receiving Postmastectomy Radiation. Int J Radiat. Keywords: Breast reconstruction, Implant loss, Radiotherapy

2260

Digital Poster radiochemotherapy for inflammatory/locally advanced breast cancer Bilal El alaoui, Wissal Hassani, François Akotegnon, Fatima zohra Zaanoun, Samia Khalfi, Kawtar Soussy, Fatima zahraa Farhane, Zenab Alami, Touria Bouhafa radiotherapy, chu hassan II, fes, Morocco Purpose/Objective: Evaluate the role of concurrent radio-chemotherapy (CRT) with capecitabine in non-resectable inflammatory/locally advanced breast cancers after a lack of response to neoadjuvant chemotherapy.