Abstract Background: Post-mastectomy breast reconstruction is a crucial component in improving psychosocial outcomes and quality of life for breast cancer survivors. Prepectoral implant-based breast reconstruction has gained traction over the past decade due to its potential to enhance aesthetic results and reduce muscle disinsertion-related complications. Wider adoption is limited by concerns over potentially higher healthcare costs compared to the previously traditionally favored subpectoral approach. Prior research on the cost implications of these methods has produced mixed results, often lacking comprehensive analyses of cumulative perioperative medical expenses. Methods: This retrospective cohort study analyzed data from women who underwent unilateral or bilateral mastectomy followed by immediate implant-based reconstruction at a single academic center between July 2017-June 2022. The study period marked a transition in institutional practice from predominantly subpectoral to prepectoral procedures. We examined billing charges from the index surgery and the downstream costs of patient care up to six months post-operation. Regression analyses assessed total index surgery costs, downstream costs, and cumulative costs, adjusting for variables such as age, BMI, and racial demographics. Results: The study analyzed data from 185 patients—86 underwent prepectoral and 99 underwent subpectoral reconstruction. Demographic analysis revealed no significant differences in baseline characteristics such as age, BMI, or intraoperative time between groups. Subpectoral reconstructions had significantly lower index surgery costs, with a 30.5% decrease in costs compared to prepectoral reconstruction (p 0.001). While downstream costs up to six months post-surgery did not significantly differ, a trend towards reduced expenses was noted following subpectoral procedures (p = 0.094). Cumulative costs, driven by initial surgery expenses, were 29.2% lower in subpectoral cases (Table, p 0.001). The increased use of acellular dermal matrix in prepectoral procedures was identified as a major factor contributing to higher costs. Conclusions: Our findings demonstrate that prepectoral implant-based reconstruction is associated with significantly higher surgical and cumulative costs compared to subpectoral reconstruction. No substantial differences were observed in postoperative care costs, suggesting that the increased expense of prepectoral approaches is primarily driven by the higher cost of surgical adjuncts during the index surgery. These results provide critical cost-related insights as prepectoral techniques, including the need to use lower-cost surgical adjuncts. Addressing these cost variables could facilitate broader implementation of prepectoral procedures, leveraging their potential patient-centered benefits. Citation Format: D. B. Lipps, B. D. Baglien, M. N. Saunders, J. Vidergar, G. L. Maica, P. L. Myers, M. Banerjee, A. O. Momoh. Cumulative Medical Costs of Prepectoral versus Subpectoral Implant-Based Breast Reconstruction: A Retrospective Analysis of a Single Academic Center 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 PS2-01-11.
Lipps et al. (Tue,) studied this question.