Abstract P2-13-01: An innovative risk-reducing approach to post-mastectomy radiation delivery following autologous breast reconstruction

Abstract

Abstract Introduction: There is no consensus among radiation oncologists regarding delivery of post-mastectomy radiation therapy (PMRT) after immediate autologous breast reconstruction, and plastic surgeons rarely participate in this decision-making process. However, radiation-induced changes markedly influence flap outcomes and affect the flap permanently. We present an innovative approach for PMRT delivery, through the use of custom bolus. This technique provides individualized, targeted PMRT to the reconstructed breast to minimize flap-related complications. Methods: All patients who underwent mastectomy with immediate autologous reconstruction between 2005 and 2014 at our institution were identified. Radiation was delivered to the reconstructed autologous breast in 29 patients. Post-irradiation complications and reconstruction outcomes were compared for patients treated with custom bolus, standard PMRT, and historical controls. Results: Over the past 10 years, 157 patients (226 breasts) underwent immediate autologous tissue breast reconstruction following mastectomy. Of the 29 patients who received PMRT, 10 were treated with custom bolus. The custom bolus uses perforated Aquaplast and a nearly tissue-equivalent wax to form a cast which conforms to the irregular contours of the chest wall, allowing for easy application through the duration of treatment. Pre-irradiation computed tomography was used to optimize dose distribution, evaluate the internal mammary vessels, and target the deeper tissues adjacent to the chest wall (minimizing dose inhomogeneity to the skin). Custom bolus resulted in fewer radiation-induced skin changes and less skin tethering/fibrosis than standard bolus (0% vs 10% and 20% vs 35%, respectively), and less volume loss and contour deformities compared with historical controls (10% vs 22.8% and 10% vs 30.7%, respectively). Conclusion: The use of custom bolus tailors radiation delivery to the internal mammary vessels, anastomoses, and skin; uniformly doses the surgical incision; and provides the necessary radiation dose to prevent recurrence, thus not compromising oncologic safety. It is easily fabricated, cost-effective and placement is straightforward and reproducible. Because radiation has negative effects on autologous breast reconstruction and often results in vascular intimal fibrosis and fat necrosis, plastic surgeons should participate in radiation planning. Our custom bolus PMRT technique reduces the incidence of these radiation effects. Citation Format: Piper ML, Evangelista M, Amara D, Daar DA, Foster RD, Fowble B, Sbitany H. An innovative risk-reducing approach to post-mastectomy radiation delivery following autologous breast reconstruction. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-13-01.