MRI‐Based Assessment of Margin Status Determinants, Preoperative Predictors, and Prognostic Outcomes in Breast‐Conserving Surgery Following Neoadjuvant Therapy

ABSTRACT Background and Purpose This MRI‐based study investigates factors influencing and predictors of margin status in neoadjuvant therapy followed by patients with breast‐conserving surgery (NAT‐BCS) and evaluates associated locoregional/distant control outcomes. Materials and Methods We conducted a retrospective analysis of 117 consecutive patients with breast cancer (BC) who underwent NAT‐BCS between June 2014 and June 2024. All patients received magnetic resonance imaging (MRI) examinations both before and after NAT. Results Univariate analysis identified factors influencing surgical margin status as molecular subtype (with HER2+ showing the lowest positive rate, followed sequentially by triple‐negative breast cancer (TNBC), Luminal B HER2+, Luminal A, and Luminal B HER2‐), nonmass enhancement (NME) on pre‐NAT MRI, axillary lymph node metastasis, post‐NAT MRI shrinkage pattern, postoperative pathological complete response (pCR) status, pN status, and lymphovascular invasion (LVI); however, multivariate analysis demonstrated that only LVI independently affected margin status, and NME on pre‐NAT MRI independently predicted margin status, with 106 patients ultimately undergoing BCS, exhibiting a locoregional recurrence (LRR) rate of 1.9% (2/106) and a distant metastasis (DM) rate of 2.8% (3/106). Conclusion The presence of NME on pre‐NAT MRI could be a predictor for margin status, possibly informing surgical strategy formulation. Concurrently, LVI might represent a distinct determinant influencing margin outcomes. NAT‐BCS therapy has achieved favorable local‐regional and distant control outcomes.