Abstract P2-01-11: SentimagIC: A non-inferiority trial comparing super paramagnetic iron oxide vs. Tc99 and blue dye in the detection of axillary sentinel nodes in patients with early stage breast cancer

Abstract

Abstract Background: Sentinel lymph node biopsy (SLNB), performed using radioisotope tracer with or without blue dye, is a highly accurate method for staging the axilla in early breast cancer. A radioisotope tracer with or without blue dye is the most commonly used technique for SLNB. Superparamagnetic iron oxide mapping agents detected by a handheld magnetic probe have been explored to overcome the disadvantages of the standard technique which include the short half-life, availability, handling and disposal issues for radioisotope, and the risk of allergic reactions to blue dye. Iron oxide mapping agents have been shown to be non-inferior to the standard technique in European studies. The SentimagIC trial was designed to establish the non-inferiority of a new formulation of the magnetic tracer, SiennaXP, to the combination of radioisotope and blue dye and was required to support a US regulatory submission. Methods: Between January and December 2015, 160 patients with clinically node negative early stage breast cancer were recruited from six centers in the United States. Subjects received radioisotope injection then an intraoperative subareolar injection of SiennaXP and isosulfan blue dye prior to SLNB being performed. The sentinel node identification rate was compared between SiennaXP and the standard technique to evaluate concordance and non-inferiority. Results: 147 procedures were completed in 147 subjects. A total of 369 histologically confirmed nodes were excised. The nodal detection rate was 94.3% (348/369) with SiennaXP and 93.5% (345/369) with the standard technique (difference 0.8%, 95% binomial confidence interval lower bound -2.1%). The per-subject detection rate was 99.3% (145/146) with SiennaXP and 98.6% (144/146) with the standard technique (one subject excluded due to not contributing any analyzable nodes). There were 22 subjects with positive SLNs, of whom 21 (95.4%) were detected by both SiennaXP and the standard tracers. In one subject, a positive node was not identified by any tracer, but was removed as clinically suspicious. The number of nodes excised per subject was 2.4 for both SiennaXP and for the standard combined technique. Conclusion: This study showed SiennaXP is non-inferior to the standard dual technique of radioisotope and blue dye for axillary sentinel lymph node detection in early stage breast cancer and this provides a potential alternative to radioisotope and blue dye. Citation Format: Alvarado M, Bold R, Gittleman M, Beitsch P, Blair S, Harmer Q, Kivilaid K, Teshome M, Thompson A, Mittendorf E, Hunt K. SentimagIC: A non-inferiority trial comparing super paramagnetic iron oxide vs. Tc99 and blue dye in the detection of axillary sentinel nodes in patients with early stage breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-01-11.