Abstract PS2-01-21: Risk Factors for Fat Necrosis Following Abdominally Based Autologous Breast Reconstruction

Abstract Background: Fat necrosis is one of the most common complications following autologous breast reconstruction. The clinical presentation of fat necrosis can mimic that of a cancerous recurrence, inducing patient anxiety and necessitating further imaging and biopsies. Furthermore, severe cases can compromise cosmetic outcomes, often requiring revisional surgery. Despite its prevalence and clinical significance, identification of specific risk factors for the development and severity of fat necrosis is poorly understood. This study, therefore, aims to identify and examine these risk factors to improve patient outcomes. Methods: We performed a retrospective review of patients who underwent autologous breast reconstruction with an abdominally based free flap at a single academic institution between September 2005 through January 2024. Data collected included demographics, surgical details, and post-operative complications (fat necrosis, infection, delayed wound healing, seroma, hematoma, necrosis, revision surgery). Chi-square and independent t-test analysis were performed to identify differences between groups, and multivariate logistic regressions were performed to assess predictors of fat necrosis. Results: A total of 434 patients (706 breasts) were included in this study. The median length of follow up after reconstruction was 4.2 years. 157 breasts (22%) developed fat necrosis, of which 68 breasts (43%) which underwent surgical excision. Average age (p=0.03) and BMI (p=0.01) were both significantly higher in the cohort that developed fat necrosis. Neither smoking status nor the presence of pre- or post-mastectomy radiation impacted rates of fat necrosis. Increased venous coupler size (p=0.01) and use of a bipedicled flap (p=0.000) were also significantly associated with the cohort that developed fat necrosis. Flap type (DIEP, msTRAM, SIEA) did not impact rates of fat necrosis. No significant differences in demographics or surgical details were found between patients that developed fat necrosis that did or did not warrant surgical management. On multivariate logistic regression, age (p=0.009, OR: 1.02), BMI (p=0.003, OR: 1.06), venous coupler size (p=0.04, OR: 1.58), and bipedicled flap reconstruction (p=0.00, OR: 6.05), were identified as independent predictors of developing fat necrosis. Conclusion: This study identifies advanced age, higher BMI, the use of larger venous couplers, and bipedicled flap as independent risk factors for the development of fat necrosis following autologous breast reconstruction. These findings can help guide preoperative patient counseling and intraoperative decision-making. Citation Format: M. Choi, A. J. Lopes, C. M. Vargas, P. Tewari, D. S. Rouhani, R. Behnam-Hanona, J. Brown, M. Lem, A. Gozali, N. Parmeshwar, M. L. Piper. Risk Factors for Fat Necrosis Following Abdominally Based Autologous Breast Reconstruction [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-01-21.