The iBRA-NET localization study: international IDEAL 2a/2b multicentre cohort study comparing the safety and effectiveness of wire- and radar-guided localization for impalpable breast lesions

Wire-guided localizations have been the historical standard for breast lesion localization; however, they have logistical constraints and can dislodge in the preoperative period. Radar-guided localization has the potential to uncouple localization from the day of surgery, but the technique needs to be evaluated in a direct comparison with wire-guided localization to ensure efficacy and safety.

The iBRA-NET localization study is a prospective platform IDEAL 2a/2b study comparing wire-guided localization with new generation localization devices. This arm describes SCOUT® radar localization for impalpable breast lesions performed between June 2021 and December 2024, compared with a historical cohort of wire-guided localization performed between August 2018 and August 2020. Primary outcome was identification of the index lesion in the excision specimen. Secondary endpoints included safety (complications), margin re-excision, magnetic resonance imaging bloom size, and specimen weight.

Data were accrued from 1297 radar localized patients in 27 units. Index lesion identification was 95.2% in radar-guided excisions versus 99.1% in wire-guided excisions (P = 0.001). In a sensitivity analysis excluding patients receiving neoadjuvant chemotherapy, identification rates were 98.9% versus 99.6% (P = 0.114). For a subset of patients having a simple lumpectomy for a unifocal, unilateral breast lesion with no neoadjuvant treatment (1627), positive margins were seen in the main excision specimen in 1003 (15.0%) wire-guided versus 624 (9.0%) radar-guided excisions (P < 0.001). Re-excision was required in 131 (13.2%) wire-guided versus 91 (14.7%) radar-guided excisions (P = 0.442). There was a significant difference in specimen weight/size2 (0.138 g/mm2 wire-guided localization versus 0.182 g/mm2 radar; P < 0.001). The median start time for surgery was earlier in the day for radar-guided localizations compared with wire-guided (12:27 versus 13:40; P < 0.001). All radar placements in axillary nodes (13) led to successful nodal retrieval.

SCOUT® radar localizations are a safe and effective localization technique in both the breast and axilla, with outcomes comparable to wires. There were demonstrable logistical advantages in operative start time when using a radar reflector.