Pathologic evaluation of lumpectomy resection margins for invasive breast cancer: a single institution's experience.

Objectives: Breast conservation therapy (BCT) or lumpectomy followed by radiation has been established as a preferred treatment for most patients with early-stage invasive breast cancer. About 20-40% of patients after initial lumpectomy will have to undergo re-excision due to a positive margin.

Methods: To determine the factors predicting higher risk of positive resection margin, we retrospectively analyzed 409 patients who underwent initial lumpectomy for invasive breast cancer from January 2019 through November 2022. Based on microscopic examination, the samples were divided into 3 subgroups with positive, close, or clean margins.

Results: Positive margin was more frequently associated with larger tumor size (P<0.0001), specified histologic type (P<0.0001), higher tumor grade (P=0.004), multifocality (P<0.0001), positive lymph node status (P=0.0005), and lymphovascular invasion (P=0.0007). Other factors were not significantly associated with margin status including HER2/ER/PR status, presence of carcinoma in situ component, age at diagnosis, and history of neoadjuvant chemotherapy.

Conclusions: From the clinical practice of individual institution, identification and comprehensive assessment of these pathologic predictors will be useful for clinical management and intraoperative surgical-decision-making to reduce the rate of re-excision.