Breast cancer: use of superparamagnetic iron oxide tracer to avoid unnecessary sentinel lymph node biopsies. The sentinot study - our local experience (Oral Presentation)

Abstract

Aim: Ductal carcinoma in‐situ (DCIS) of breast does not metastasize to regional lymph nodes. However disease upstaging to invasive disease are not uncommon on final histopathology. Performing sentinel lymph node biopsy (SLNB) at a second operation has been considered difficult and unreliable especially in patients receiving mastectomy. Superparamagnetic iron oxide (SPIO) is a new tracer agent that resides in sentinel lymph nodes for more than 30 days. The aim of this prospective study is to evaluate this novel role of SPIO in avoiding unnecessary SLNB. Methods: Eligible patient with pure DCIS on core biopsy will receive subareolar SPIO injection in primary breast operation. A delayed SLNB will be performed in 4 weeks from initial operation if the final histopathology shows invasive carcinoma. Primary outcome is the number of patients who can avoid a SLNB and the secondary outcome is the success rate of a delayed SLNB with SPIO. Results: Thirty‐three eligible patients were recruited from May 2018 to June 2020. The mean age was 62 (range 39‐77). Sixteen patients (48.5%) had high‐grade DCIS on core biospy and ten of them were mass‐forming. Twenty‐eight patients (84.8%) received mastectomy. In total, pure DCIS was found on final histopathology in twenty‐six patients (75.8%) and all of them avoided a SLNB. Seven patients with invasive carcinoma, including six with mastectomy, had a successful delayed SLNB. Conclusions: SPIO is a reliable tracer agent that allows delayed SLNB. Breast cancer patients with DCIS on core biopsy can potentially avoid an axillary overtreatment.