Abstract PO5-19-02: I-PREPARE: International Prospective REgistry on Pre-pectorAl breast Reconstruction (EUBREAST 11R-NCT 05817175)

Abstract Background: Despite the progressive de-escalation of breast cancer (BC) surgery, mastectomy rates remain around 30-40%. Furthermore, up to 1/3 of BC patients undergo a contralateral risk-reducing mastectomy and around 40% of mutation carriers choose a bilateral intervention. To date, immediate breast reconstruction (IBR) with implants is the most commonly performed reconstructive procedure. After an initial experience with implants in subcutaneous positioning under the mastectomy flap in the seventies, this technique was abandoned due to a high rate of implant loss (28%), flap necrosis (13.5%) and capsular contracture (56%). For this reason, the positioning of the implant under the pectoralis major has become the standard of care. However, over time surgical techniques and implants have improved, resulting in decreasing implant loss, flap necrosis and capsular contracture rates. Moreover, biological/synthetic meshes have been used to cover the implant placed over the pectoralis major, thus avoiding to mobilize the muscle with some benefits in terms of reduced complications (no animation deformity, no chronic pain, no loss of muscular function), patients’ wellbeing, postoperative pain and recovery. Additionally, recent literature reported encouraging results with polyurethane breast implants in pre-pectoral positioning without any kind of implant coverage. Although these procedures are considered safe they were not evaluated in prospective randomized trials. In 2019 a joint consensus on pre-pectoral breast reconstruction (PBR) clearly recommended to properly audit the results in terms of surgical complications and patient-reported outcomes. Based on these premises the EUBREAST (European Breast Cancer Research Association of Surgical Trialists, www.eubreast.org) study group decided to launch a prospective international cohort study aimed at comparatively evaluating data on different surgical techniques of PBR with or without PMRT. Therefore, we will prospectively evaluate the utilization of PBR, including surgical, oncological, aesthetic and patients’ satisfaction and quality of life outcomes related to each type of surgical technique and the interaction with post-mastectomy radiation therapy (PMRT). Eligibility criteria: - Female patients age≥18 years - Signed informed consent - Patients undergoing mono/bilateral therapeutic mastectomy and immediate PBR Exclusion criteria - Patients not suitable for surgical treatment - Patients undergoing subpectoral reconstruction, reconstruction with tissue expander or autologous IBR Specific aims: The primary endpoint is implant-loss at 3 months defined as the unplanned removal or loss of the implant, as a result of infection or any other complication Secondary endpoints are infection, re-admission and re-operation rates, quality of life evaluated through BREASTQ Breast Reconstruction Module and EQ-5D-5L questionnaires on an App for patients before and after breast reconstruction at 6, 12, 24 months, early onset complication at 3 months, late-onset complications at 6, 12, 24 months, further surgery at 24 months, time to adjuvant therapy. Tertiary endpoints are further surgery, loco-regional recurrence, disease free survival, breast cancer specific survival, distant-disease free survival, overall survival, development of seroma/breast implant-associated anaplastic cell lymphoma. Statistics: We will use a single-arm design to assess the surgical safety of PBR through implant loss rate at 3 months which is expected to be ≤9% based on previous literature; 12% or greater will be regarded as unacceptably high. The assessment will be based on 1,112 patients. For this sample size calculation, power was set to 90%, and the two-sided alpha was set to 0.05. Allowing for a 10% loss to follow-up at 3 months, we aim at recruiting 1,236 patients. Accrual has not started yet. Funding: EUBREAST ETS Italy Contact: Oreste Davide Gentilini: gentilini@eubreast.org Citation Format: Rosa Di Micco, Maggie Banys-Paluchowski, Maria-Joao Cardoso, Jana de Boniface, Bahadir M. Gulluoglu, Orit Kaidar-Person, Thorsten Kühn, Maurizio Bruno Nava, Philip Poortmans, Shelley Potter, Nicole Rotmensz, Tanja Spanic, Marc Thill, Luzia Travado, Walter Weber, Oreste Davide Gentilini. I-PREPARE: International Prospective REgistry on Pre-pectorAl breast Reconstruction (EUBREAST 11R-NCT 05817175) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-19-02.