Clinicopathological and imaging factors of surgical margin status and prognosis in breast-conserving therapy.

‌To identify factors influencing margins, re-excision rates, and prognosis in breast-conserving surgery (BCS) patients, and compare the accuracy of ultrasonography (US), mammography (MG), and magnetic resonance imaging (MRI) in assessing tumor size, axillary lymph node status and margins using pathology as the gold standard.‌ A retrospective analysis was conducted on 2775 consecutive invasive breast cancer patients who receive BCS between June 2014 and June 2024. All patients underwent preoperative US, MG, and MRI. The positive margin rate was 18.2% (506/2775).‌ Independent predictors of margin status included pT, lymphovascular invasion (LVI), extensive intraductal component (EIC), US-measured tumor size, MRI-based abnormal enhancement extent, fibroglandular tissue (FGT), background parenchymal enhancement (BPE), non-mass-like enhancement (NME), and axillary lymph node metastasis (ALNM). Factors influencing margin status varied significantly across MRI tumor size subgroups and molecular subtypes. US demonstrated the highest accuracy for preoperative tumor size assessment, while MRI outperformed other modalities in evaluating resection margin status and ALNM. Among 2,450 patients who successfully underwent BCS, the reoperation rate was independently associated with HER2, EIC, MRI abnormal enhancement extent, FGT, BPE, and ALNM. The local-regional recurrence (LRR) rate was 2.5%, with independent predictors including age, molecular subtype, LVI, EIC, MRI abnormal enhancement extent, BPE, ductal pattern orientation, and radiotherapy status.‌ Preoperative imaging and molecular subtyping provide critical insights into margin status and recurrence risk in BCS patients. Tailored surgical planning and adjuvant therapy based on these factors may optimize clinical outcomes and reduce recurrence rates.