Sentinel lymph node biopsy in breast cancer after neoadjuvant therapy using a magnetic tracer versus standard technique: A multicentre comparative non-inferiority study (IMAGINE-II)

Abstract

IntroductionPrevious studies have shown that a magnetic tracer technique using superparamagnetic iron oxide (SPIO) and a manual magnetometer (Sentimag, SM) is as effective as the standard technique using a radioisotope injection and a gamma probe (GP) for the detection of sentinel lymph nodes (SLNs) in breast cancer (BC) patients. This study was designed to investigate the performance of SM for post-neoadjuvant (NAT) SLN biopsy in BC patients. Materials and methodsPost-NAT BC patients were recruited from five centres. Readings of SLNs were recorded in transcutaneous, intraoperative and ex vivo scenarios by both GP and SM techniques. SLNs were assessed by OSNA (One-Step Nucleic Acid Amplification). ResultsA total of 89 patients were included. At the patient level, the transcutaneous and intraoperative SLN detection rate was 97.8% by both techniques. At the node level, the GP detection rate intraoperatively was lower than that of SM (93.8% vs. 99.2%), with a concordance rate of 93% (90% CI 1.25; 9.44). The ex vivo detection rate was lower for GP compared to SM both per patient 96.6% vs. 97.8%, and per node 90.6% vs. 98.4% (90% CI -2.03; 4.22 and 1.82; 13.68, respectively). Furthermore, the detection rate of pathologically positive SLNs per patient and per node was lower for GP than SM both intraoperatively and ex vivo. These results showed the non-inferiority of SM intraoperatively per node (90% CI -4.89; 20.89) and ex vivo per patient (90% CI -2.38; 29.66). ConclusionOur study showed the non-inferiority of SM compared to GP for detecting SLNs in post-NAT BC patients.