An adapted protocol for magnetic localisation of nonpalpable breast cancer lesions and sentinel lymph nodes using a magnetic seed and superparamagnetic iron oxide tracer

Background: Localisation techniques for nonpalpable breast cancer lesions and sentinel lymph node biopsy (SLNB) are associated with several drawbacks. A complete magnetic technique using magnetic seeds and superparamagnetic iron oxide tracer could be an interesting alternative. This study describes a clear protocol and the results of a combined magnetic approach. Methods: From August 2021 to February 2022 40 patients undergoing breast conserving surgery with SLNB were eligible for inclusion. Localisation was performed under ultrasound or stereotactic guidance, 1 week before surgery. Subsequently, 1 ml of tracer was injected at least 4 cm away from the tumour. Technetium-99m ( ^99mTc) was injected 1 day before surgery as control procedure. Outcomes were SLNB time, a number of nodes detected with magnetic tracer including comparison with ^99mTc, a success rate of malignant lesion detection and pathological margin assessment. Results: In total, 40 procedures were performed on 39 patients. A median of one node was retrieved. Sentinel nodes were retrieved using MagTrace® with a 92.5% detection rate compared to ^99mTc. Wide local excision under magnetic guidance was successful in 35 cases. Conclusions: This paper describes a combined magnetic approach for breast-conserving surgery and SLNB. An adapted protocol is described and could be used for implementation.