Use of a Magnetic Tracer for Sentinel Lymph Node Detection in Early-Stage Breast Cancer Patients: A Meta-analysis

Background: Sentinel lymph node (SLN) dissection involves lymphatic mapping and selective removal of clinically negative lymph nodes at highest risk for harboring metastases. Lymphatic mapping is most often performed using radioisotope with or without blue dye (standard tracers). Sienna+^®, a superparamagnetic iron oxide that can be detected using the Sentimag^® magnetometer, is an alternative mapping agent to identify SLNs that has been investigated in five clinical trials. This meta-analysis was performed to determine if Sienna+^® is non-inferior for SLN detection when compared to standard tracers. Methods: Five clinical trials comparing Sienna+^® to a standard technique were identified, and data from these studies were used to determine the agreement by Kappa statistic between Sienna+^® and standard tracers in identifying SLNs and malignant SLNs. The trials included 1683 SLNs identified in 804 patients. Data from the studies were imbalanced, therefore additional agreement indices were utilized to compare techniques. The estimated difference between the techniques was analyzed and a margin of ≤5 % was used to determine non-inferiority. Results: Agreement between the Sienna+^® and standard tracers was strong for SLN detection by patient [prevalence-adjusted bias-adjusted kappa (PABAK) 0.94, 95 % confidence interval (CI) 0.89–0.98], moderate to substantial for SLN detection by node (PABAK 0.68, 95 % CI 0.54–0.82), and strong for the detection of malignant SLNs by patient (PABAK 0.89, 95 % CI 0.84–0.95). Sienna+^® demonstrated non-inferiority compared with standard tracers. Conclusions: The Sienna+^® mapping agent is non-inferior to the standard method for SLN detection in patients with clinically node-negative breast cancer.