Initial Experience Using Magseed for Breast Lesion Localization Compared With Wire-Guided Localization: Analysis of Volume and Margin Clearance Rates.

Abstract

Detection of nonpalpable lesions requiring surgical intervention has increased during the past several decades. Techniques have evolved to help surgeons locate lesions in the operating room. Disadvantages of wire localization has led to the use of new approaches for surgical guidance. Magnetic seeds have been suggested to improve workflow and cosmetic result. This retrospective cohort study analyzed consecutive patients undergoing lumpectomy or excisional biopsy with the guidance of wire localization or magnetic seeds. The optimal and total resected volumes were calculated from pathology records, and the calculated resection volumes were compared by localization approach. Margin positivity and need for reoperation were reviewed and compared. Each group included 148 patients. The majority were treated with lumpectomy and did not undergo preoperative chemotherapy. The operative characteristics did not vary by group. Considering only lumpectomy cases, total volume resected (13.7 vs. 17.1; p = 0.003) and calculated resection ratios (1.8 vs. 2.5; p = 0.02) were significantly lower in the magnetic seed group. The rates of positive margins (10% vs. 14%) and reoperation (12.8% vs. 17.3%) were non-significantly lower than in the wire localization cases. Magnetic seeds were successfully used for lesion localization in this cohort. Pathologic examination of specimens suggested that the surgeons were able to remove closer to optimal volumes of tissue than those using wire-guided intervention. Removal of less tissue did not result in higher rates of margin positivity or a need for re-intervention to achieve negative margin status. Magnetic seeds are a feasible and non-inferior approach that overcomes many drawbacks of other localization methods.