Non-Wire Bracketed Localization Techniques and Decreased Margin Positive Rates in Breast Cancer

Breast conserving therapy (BCT) for nonpalpable lesions can be performed using various localization devices. For larger or multifocal lesions, "bracketing" with multiple localizers is required for complete excision. SAVI Scout utilizes radar localization (RL) to target clip location(s), while SmartClip employs electromagnetic chips (EMC) to provide 3D navigation and distinguish up to three devices. This study aimed to compare the excision of breast lesions using non wire localization devices such as EMC and RL versus traditional wires.

A single institution, retrospective study was conducted from August 25, 2020 to August 6, 2024, comparing EMC, RL, and wire localization in bracketed BCT. Case length, positive margins requiring re-excision, and complete retrieval of localizers in a single specimen were analyzed. Statistical analyses were performed using Kruskal-Wallis, and χ² or Fisher's exact tests.

A total of 118 cases were analyzed: 43 wire, 44 RL, and 31 EMC cases. The groups were similar in lesion size and number of localizers used (P = .736 and P = 1.000, respectively). There were fewer positive margins when EMC or RL were utilized (EMC 29%, RL 22.7%, wires 50%, P = .022). EMC was also associated with significantly shorter operative times (33.9 minutes vs. RL 45.6 minutes, wire 40 minutes, P = .025). There was no significant difference in complete retrieval of localizers among the groups (EMC 93.5%, RL 97.7%, wire 100%, P = .264).

Non-wire localization method is effective for bracketed BCT with lower rates of margin positivity and faster operative times with EMC. This supports their use in BCS, especially when multiple localizers are needed.