Supermagnetic Iron Oxide Tracer in Association with Radioisotope, for Sentinel Node Biopsy in Patients with Complete Axillary Response, After Neoadjuvant Chemoterapy: A Single Center, Prospective Study

Abstract

Although NAC has been shown to be very effective in down staging of the axillary cavity and a complete pathological response (pCR) has been observed in 40-70% of cases (above all in triple negative and Her2+ patients), it was assumed that a pathological response of the tumor alter axillary lymphatic rainage for lymphatic canal fibrosis with cellular debris, reducing the probability of sentinel node (SLN) idetification, with a likely increase in the percentage of false negatives rate (FNR), which as shown by SENTINA trial, where it stands at values of 16%, with a detection rate (DR) of 80%. In light of these observations, different surgical strategies have been put in place to reduce the FNR rate, in order to imporve the number of sentinel/parasentinel nodes and the identification rate (IR) during SNLB in c N+ yc N0 patients, such as the use of double tracer (like vital dye or superparamagnetic iron oxide- SPIO, in association with Tc99), the clip placement in nodes involved before NAC and intraoperative ultrasound (IOUS). Here we will report our experience about the detection rate (DR) and the feasibility of the double tracers, SPIO (Magtrace) + Tc99. We enrolled 20 patients with diagnosis of invasive breast cancer with axillary metastasis, undergoing neodjuvant chemiotherapy and in axillary response after this (cN+ycN0). The overall lymph nodes removed were n°64 between sentinel and parasentinel nodes (52 with Magtrace and 29 with technetium, p-value 0.05). In 12/20 patients (60% of cases) the complementary use of Magtrace allowed us to reach a number of identified lymph nodes ≥ 3, avoinding axillary node dissection in 15/20 (75% of all patients). As demonstrated by our experience, still limited in number of cases, Magtrace® is a valid support in finding the SLN post NAC, both in terms of non-inferiority compared to Tc99, and as a complementary means to the latter in the 'to help us find a number ≥ 3 of LS, essential for breaking down the FNR.