ThP2.5 - Number of lymph nodes removed in SLNB: comparison between standard technique versus Magtrace from a single-centre study

Abstract Introduction Sentinel lymph node biopsy (SLNB) is a precise method for axillary staging in early breast cancer. Historically, the standard approach used radioisotope, often combined with blue dye, for localising the sentinel lymph node (SLN). Recently, the introduction of the superparamagnetic iron oxide mapping agent, Magtrace, offers an alternative. Following the adoption of Magtrace, there was a perception that more nodes were being removed during SLNB. This study aims to compare the number of lymph nodes removed, during SLNB, between both techniques. Methods A retrospective single-centre study (2022-2023) included 316 patients undergoing SLNB at Royal Lancaster Infirmary. Before the late 2022 adoption of Magtrace, the standard technique involved radioisotope+/-blue dye. Subsequently, based on consultant preference, patients received Magtrace alone or with blue dye. The comparison focused on the number of identified SLN between the magnetic and standard techniques. Results Data from 316 patients was analysed across two periods: March to October 2022 (standard technique n=160), and March to October 2023 (Magtrace n=120; Magtrace+blue dye n=30; blue dye only n=5). Comparative analysis of the number of nodes removed produced the following results: standard technique 2.425, magnetic technique alone 2.403, magnetic technique with blue dye 2.133, and blue dye only 1.6. Conclusion Despite initial concerns regarding the perceived increase in the number of nodes removed during SLNB with the implementation of the Magtrace technique, our study reveals that the use of this technique results in a reduction in the number SLNs removed in comparison to the standard dual technique.