Abstract PS2-03-22: Retromamamry breast-conserving surgery and volume displacement with diced acellular dermal matrix for operable breast cancer

Abstract Objective: In a previous clinical study, we demonstrated that it is feasible to perform volume displacement using diced acellular dermal matrix (dADM) immediately after breast-conserving surgery (BCS) in patients with operable breast cancer. However, we realized that unexpected non-infectious erythema could present as a complication, which led us to develop a new approach to address this issue. Summary Background Data: Previous study proved dADM was effective to fill the defect in the breast after BCS, however, some patients showed intramammary fat necrosis during adjuvant chemotherapy or postoperatively following non-infectious erythema on the skin over the cavity filled with dADM. We take into consideration of embryological characteristics of breast to minimize this complication by changing approach route through retromammary plane, while maintaining its proven advantage. Methods: After institutional review board approval, we prospectively recruited 530 breast cancer patients requiring BCS from August 2019 to June 2022. Incision was made along the periphery of breast mound including axilla or inframammary fold, where the minimum distance was expected from the incision to the index tumor. After breast cancer removal, cavity was filled with dADM. After surgery, all patients received adjuvant local irradiation treatment, systemic chemotherapy, targeted agent or endocrine treatment according to the recommendations of international treatment guidelines according to the type of molecular subtype. All enrolled patients were followed up at 2 months after completion of both chemotherapy and external radiation treatment and up to 3 years from the date of surgery, including systemic evaluation to assess the occurrence of any complications, including non-infectious erythema, and oncologic outcome related to locoregional recurrence or systemic metastasis. Results: Of 530 patients enrolled, only 5 patients showed intramammary fat necrosis. Locoregional recurrence and systemic metastasis rates were also not statistically different from previous results not included in this study. Conclusions: Retromammary BCS and volume displacement with dADM for operable breast cancer is effective for reducing fat necrosis postoperatively, even after repetitive episodes of neutropenia during systemic chemotherapy, and is easy to preserve preoperative breast mound volume and shape. Although further clinical studies are needed in a larger number of patients, we believe that this surgical method could be another oncoplastic BCS that can overcome the limitations of conventional BCS. Citation Format: J. Schneider, Y. An, H. Choi, Y. Suh. Retromamamry breast-conserving surgery and volume displacement with diced acellular dermal matrix for operable breast cancer [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 PS2-03-22.