Hyperbaric Oxygen Therapy to Improve Autologous Fat Graft Intake in Irradiated Breast

This is a prospective, monocentric, randomized controlled phase II crossover clinical trial designed to evaluate the efficacy and safety of hyperbaric oxygen therapy (HBOT) in improving fat graft retention following autologous fat transfer (AFT) in breast reconstruction for patients with prior radiotherapy. AFT is widely used in breast reconstruction but is often less effective in irradiated tissues due to reduced vascularization and oxygenation, which compromises graft survival. HBOT, which involves breathing 100% oxygen at 2.5 atmospheres absolute (ATA), has been shown to promote angiogenesis and tissue oxygenation, potentially improving fat graft integration and reducing complications in irradiated tissues. The study will enroll 16 adult female patients who have undergone radiotherapy as part of their breast cancer treatment and are scheduled to receive two sessions of AFT. Each participant will be randomized to one of two sequences: * Sequence AB: AFT alone (control) followed by AFT + HBOT (intervention) * Sequence BA: AFT + HBOT followed by AFT alone HBOT will be administered in five sessions (1 on Day 0, 2 on Day 1, 2 on Day 2), beginning immediately after the fat grafting procedure. Each session consists of 100% oxygen inhalation at 2.5 ATA for 90 minutes. Postoperative MRI will be performed six months after each AFT session to assess the volume of retained graft. Primary Objective: To determine whether HBOT significantly improves fat graft retention in irradiated breast tissue, assessed as the percentage of volume retained (measured by MRI) six months postoperatively. Secondary Objectives: * To assess the absolute fat volume retention in milliliters * To evaluate the safety and tolerability of HBOT in this setting * To assess the incidence of clinical and radiological complications (e.g., infection, hematoma, oil cysts, liponecrosis) The crossover design minimizes inter-patient variability by allowing each patient to serve as her own control. Randomization occurs immediately after the first AFT session. The anticipated duration of participation per subject is approximately 12 to 18 months, and the total study duration is estimated at 3 years (from November 2025 to November 2028).