A Multicenter Non‐Inferiority Randomized Controlled Trial of Sentinel Lymph Node Biopsy in Early Breast Cancer: Conventional Dual Tracer Versus Superparamagnetic Iron Oxide

BACKGROUND: The gold standard for detecting sentinel lymph node (SLN) in early breast cancer is combined use of radioisotope and blue dye. A newer agent, superparamagnetic iron oxide (SPIO), was developed to address the challenges faced with the traditional method. This study aims to compare the detection rate of SLN biopsy and show the non-inferiority of SPIO. METHODS: From March 2021 to April 2024, patients with clinically and radiologically node-negative breast cancer were randomized to receive SPIO-only injection or dual tracer for SLN localization. The primary endpoint was the SLN identification rate in both arms. RESULTS: 148 patients were in the SPIO group with 153 SLN procedures performed. SLN localization failed in one patient. The identification rate was 99.3% (95% CI: 95.8-99.9). 149 patients were in the dual tracer group with 156 SLN procedures done. The identification rate was 100% (95% CI: 97.0-99.9). The absolute difference was 0.7% (95% CI: -1.2 to 2.7). CONCLUSION: Our results suggest that SPIO, as a single agent, used in SLN biopsy for early breast cancer is non-inferior to the dual tracer method. It can serve as a good alternative to radioactive isotope and blue dye. TRIAL REGISTRATION: CUHK CREC Ref No. 2019.677-T (https://www.crec.cuhk.edu.hk/).