ESTRO 2025 - Abstract Book

S576

Clinical - Breast

ESTRO 2025

3467

Digital Poster Immediate implant breast reconstruction and post-mastectomy radiation therapy using Helical Tomotherapy: Results from the MARTA phase II trial Carole Massabeau 1 , Leonor Chaltiel 2 , Hélène Charitansky 3 , Françoise Izar 1 , Audrey Keller 1 , Céline Dalmasso 1 , Ciprian Chira 1 , Mony Ung 4 , Jean-Louis Lacaze 4 , Adeline Petit 5 , Charlotte Vaysse 6 , Gabrielle Selmes 6 , Eva Jouve 6 1 Radiation Department, Oncopole Claudius Regaud, Toulouse, France. 2 Biostatistics and Health Data Science Unit, Oncopole Claudius Regaud, Toulouse, France. 3 Surgery Department, Institut Bergonié, Bordeaux, France. 4 Medical Oncology Department, Oncopole Claudius Regaud, Toulouse, France. 5 Radiation Department, Institut Bergonié, Bordeaux, France. 6 Surgery Department, Oncopole Claudius Regaud, Toulouse, France Purpose/Objective: Immediate implant breast reconstruction (IIBR) is increasingly performed, even in the context of post-mastectomy radiation therapy (PMRT), due to advances in radiotherapy, particularly intensity-modulated radiation therapy (IMRT). However, prospective data on this combination remain limited. This study aimed to confirm that IIBR does not delay the initiation of adjuvant treatments and to evaluate the rate of complications and reconstruction failures when using Tomotherapy for adjuvant radiation therapy (RT). Material/Methods: In the single-arm, bicentric phase 2 MARTA trial (NCT03627988), we enrolled patients with operable, non inflammatory breast cancer who were candidates for retropectoral IIBR and adjuvant RT. Chest wall clinical target volume (CTV) delineation followed ESTRO guidelines a and excluded the implant itself (Figure 1).

Adjuvant RT was delivered using Helical Tomotherapy with 50 Gy in 25 fractions, targeting the chest wall with or without lymph nodes. The primary endpoint was the success rate of IIBR in the context of PMRT, defined by adherence to the deadlines for initiating adjuvant therapy (≤ 6 weeks for chemotherapy (CT) and ≤ 12 weeks for RT) and the absence of implant removal within one year following surgery. Results: From June 2019 to May 2023, 66 patients were enrolled, of whom 55 were evaluable. Non-evaluable patients included those for whom radiation was not indicated (n=5), those who experienced postoperative complications leading to implant removal (n=5), and one with bilateral cancer. CT was administered as neoadjuvant (38.2%) or adjuvant (43.6%). A definitive implant was used in 43 patients (78.2%), and an expander in 12 patients (21.8%). Forty patients (72.7%) also received lymph node irradiation. Dosimetric results are shown in the table 1.