The superparamagnetic iron oxide is equivalent to the Tc99 radiotracer method for identifying the sentinel lymph node in breast cancer.

Preoperative injection of Tc99 is standardly performed before sentinel lymph node biopsy (SLN) for breast cancer. Multiple questions have arisen concerning appropriate technique for SLNBs including site of injection, timing and injection material. The aim of this study was to assess the concordance between a new method, superparamagnetic iron oxide (SPIO) and the Tc99 radiotracer to identify the SLN in early breast cancer. Between July 2013 and March 2014, 120 patients with clinically node negative early breast cancer were included in the study. Patients were injected the day before the radiotracer for lymphoscintigraphy and injected the SPIO subareolar intraoperatively. SLN was excised if it was radioactive, magnetic or palpable. Patients signed an inform consent. There was no drainage by either technique in 2 patients, so this leaves 118 patients for further analysis. Detection rate by Tc 99 was successful in 113 (95.7%%) patients and by SPIO in 116 (98.3%). Concordance rates per patient between techniques was 98.2%. The SLN was positive in 36 (30%) patients. Of this, SLN positivity was detected by both techniques in 32 patients. Mean number of SLNs by 99Tc and SPIO were 1.9 and 2.21 respectively (p = 0.001). Detection of SLNs with SPIO allows for easy identification of axillary nodes, at a frequency not inferior to the radiotracer. It is an oncologically safe procedure, facilitates patients and operative room management and can be used to reliably identify SLNs in breast cancer.