Use of superparamagnetic iron oxide (SPIO) versus conventional radioisotope and patent blue dye in sentinel lymph node detection for breast cancer: preliminary results of a randomized controlled trial

Abstract

Aim: Superparamagnetic iron oxide (SPIO) has emerged as an non‐inferior tracer in sentinel lymph node (SLN) localization in early breast cancer. We have published in our previous research that it can be used alone as the only tracer agent in SLN biopsy. This is the first randomized controlled trial to directly compare the two techniques. Methods: Patients diagnosed with clinically node‐negative invasive breast cancers are randomized into Group A (SPIO) and Group B (Conventional). Patients’ background information and tumor characteristics are prospectively collected. The primary outcome is the SLN detection rate between the two groups. Other secondary outcomes include the number of SLN harvested and duration of the operation. Results: Fifty‐seven patients were recruited since July 2018, including 22 patients in SPIO group and 35 patients in conventional group. Patients’ characteristics, choices of operation and tumor biology did not differ between the two groups. The SLN detection rate was 100%. Twenty‐three percent of patients in conventional group and 21 % in SPIO group had positive SLN. The mean number of SLN harvested were 3.3 and 2.5 for SPIO group and conventional group respectively (P = 0.065). The mean duration of operation was longer for SPIO group (42.6 min vs 24.1 min, P = 0.15). However, the mean duration of operation did not show significant difference (14.9 min vs 12.3 min, P = 0.64) when the number of SLN harvested was taken into account. Conclusion: SLN biopsy with superparamagnetic iron oxide is an equally efficient and safe alternative compared with the conventional dual tracer method.