Postoperative Outcomes Following Autologous Breast Reconstruction in Patients Receiving Selective Estrogen Receptor Modulators and Aromatase Inhibitors: A Multicenter Propensity Score‐Matched Cohort Study

BACKGROUND: The perioperative management of endocrine therapy remains controversial in patients undergoing autologous breast reconstruction. Because selective estrogen receptor modulators (SERMs) and aromatase inhibitors (AIs) differ in their mechanisms of action and adverse-effect profiles, we evaluated their associations with postoperative outcomes separately in a large multicenter propensity score-matched cohort. METHODS: This retrospective TriNetX study included patients undergoing autologous breast reconstruction. Preoperative exposure was defined as a documented SERM or AI prescription within 3 months of reconstruction. Exposure cohorts were mutually exclusive, and controls excluded both endocrine therapy classes. Separate 1:1 propensity score matching incorporated demographic, comorbidity, oncologic, treatment, venous thromboembolism, and antithrombotic covariates. Outcomes were assessed within 90 days. RESULTS: After matching, 1993 SERM-exposed patients were compared with 1993 controls and 3167 AI-exposed patients with 3167 controls. SERM exposure was not significantly associated with evaluable 90-day outcomes, including coded postoperative debridement (3.01% vs. 2.56%; RR, 1.18; 95% CI, 0.81-1.73; p = 0.39). AI exposure was associated with increased coded postoperative debridement (4.45% vs. 3.38%; RR, 1.33; 95% CI, 1.03-1.72; p = 0.028), while other evaluable outcomes were not significantly different. AI exposure was also associated with greater debridement hazard (HR, 1.44; 95% CI, 1.12-1.87; p = 0.0049). CONCLUSIONS: Documented SERM exposure was not significantly associated with evaluable postoperative outcomes, whereas AI exposure was associated with increased coded postoperative debridement. Because debridement codes lack anatomical specificity, this finding is exploratory and does not establish flap-specific compromise. These separate analyses do not establish differences between endocrine therapy classes or support recommendations regarding perioperative continuation or discontinuation.