A combined, totally magnetic technique with a magnetic marker for non-palpable tumour localization and superparamagnetic iron oxide nanoparticles for sentinel lymph node detection in breast cancer surgery

Background: Surgery for non-palpable breast cancer may often be a challenging procedure. Recently, a magnetic seed (Magseed^®) used for tumour localization has been developed. Superparamagnetic iron oxide nanoparticles (SPIO) for sentinel lymph node (SN) detection is a novel tracer that may be injected up to four weeks preoperatively. This study is the first combining the magnetic seed and SPIO.

Material and methods: Patients planned for breast conserving surgery and SN-biopsy (SNB) were recruited from two units in Sweden. Patients underwent lesion localization with Magseed^® and SPIO injection (Magtrace™) by the breast radiologist in the preoperative period. Feasibility of successful lesion localization and excision together with a successful SNB detection was evaluated. Seed migration, number of SNs, specimen volume and calculated resection ratio (CRR) were reported.A survey of the physicians' experience was conducted.

Results: Localization was performed at a median of three days before surgery (range 0-25). All 32 patients underwent microscopically radical resection with a CRR of 1.49. No seed migration was noticed. SNB was successful in all patients. A median of two SNs was retrieved. Radiologists and surgeons reported the procedure easy to learn and outperformed guidewire localization in terms of localization and excision time. They thought the technique facilitated planning localization and surgery.

Conclusions: The combined magnetic technique provided accuracy in tumour localization and SN detection without excess tissue excision and with promising results for flexibility in delivery of care. Larger studies are needed to confirm these findings.