Correlation between ferromagnetic and isotopic tracers for sentinel lymph node detection in cutaneous melanoma: IMINEM study

Background The usefulness of sentinel lymph node biopsy (SLNB) in staging cutaneous melanoma has been proven. Therefore, different tracers have been used to identify the sentinel lymph nodes (SLNs). The use of isotopic tracers together with radioactivity detectors allowed a much more precise and direct approach to the SLNs. However, not all centres have access to a Nuclear Medicine department hindering sentinel lymph node detection (SLND) and consequently, other markers such as ferromagnetic tracers have been evaluated looking for the same advantages and effectiveness as isotopic tracers. Ferromagnetic tracers have proven their usefulness in other cancer entities such as breast, prostate and thyroid cancer. The objective was to assess the detection and concordance rates between isotopic and ferromagnetic techniques for SLNB in cutaneous melanoma. Method Isotopic SLNB technique and ferromagnetic tracer were compared for cutaneous melanoma in a non‐inferiority multicentre prospective study carried out in six Spanish hospitals. Results A total of 60 patients were recruited and 133 lymph nodes removed. The detection rate was slightly higher with ferromagnetic tracer in head‐neck and trunk melanomas, and with isotopic tracer in limbs. The patients' and nodes' concordance rates between both techniques for ex vivo samples were 95% and 86% for head‐neck and trunk tumours and 97% and 93% for limbs tumours, respectively. The concordance rates for involved nodes were 100% and 88.2% for patients and nodes, respectively. Conclusion The intraoperative detection and biopsy of SLN in cutaneous melanoma using a ferromagnetic was a reliable alternative method to the isotopic technique in cutaneous melanomas.