72229 - Ultralow dose of superparamagnetic iron oxide nanoparticles in combination with Magseed for sentinel node detection in nonpalpable breast cancer

Abstract Introduction A nonpalpable breast cancer can be localized using a magnetic seed (Magseed). Sentinel lymph node (SLN) detection with superparamagnetic iron oxide (SPIO) nanoparticles is comparable to Technetium (Tc99) +/- blue dye (BD). The study aim was to evaluate the feasibility of the combined use of a Magseed and an ultra-low, intradermal SPIO dose. Method Women from the Magsnow 2.0 study with non-palpable breast cancer planned for SLN-biopsy and breast tumour localisation with Magseed were selectively included for this subgroup analysis. The patients received 0.1 mL SPIO up until 30 days prior surgery, as well as Tc99 +/- BD according to routine. SPIO was injected by the surgeons in Gothenburg and by radiologists in Västerås. The SPIO was usually injected more than 2 cm away from the Magseed. Analyses of surgical margins, reoperations and SLN detection were made. Surgeons was asked about their experience with the combination on a scale from 1-10. Result In total, 20 women were included. SLN detection was 95% (19/20) with SPIO and 100% with Tc99 +/- BD. The median number of SLNs was three and metastases were found in five patients (25%). Mean minimum surgical margin was 6.5 mm (range 0.36-16 mm) and no reoperations were needed. The feasibility of indication with Magseed in combination with SPIO according to the operating surgeons was high, eight surgeons rated a mean value of 7,8 (1-10). Discussion In women with nonpalpable breast cancer undergoing breast conserving surgery, the combination of Magseed and SPIO seems to be feasible even though an ultralow dosage were used.