Sentinel Lymph Node Biopsy in Early Breast Cancer: Magnetic Tracer as the Only Localizing Agent

Abstract

Background The combined use of radioisotope and blue dye is the gold standard in sentinel lymph node (SLN) localization in early breast cancer. Superparamagnetic iron oxide (SPIO) has recently emerged as a non-inferior new tracer in sentinel lymph node mapping with fewer disadvantages. This study represents the first and the largest cohort of superparamagnetic iron oxide application in Asian population. Methods Retrospective analysis of a prospectively maintained database was performed from August 2016 to December 2017. All patients with SLN localization by SPIO were included in this study. Results A total of 328 breast cancer patients with 333 SLNB procedures were included in this study. Median age was 54 years (range 32–86). Median tumor size was 1.9 cm (range 0.1–12 cm).There were 138 breast-conserving surgeries and 195 mastectomies. All patients received injection of SPIO 1 day prior to operation. A total of 329 successful sentinel lymph node biopsy (SLNB) procedures were undertaken with 1514 sentinel lymph nodes (SLNs) identified. One hundred and fifty-three (10.1%) of the SLNs were positive for malignancy. There were 54 patients with macrometastases, 26 with micrometastases and 24 with isolated tumor cells. Sixty-seven patients underwent subsequent axillary dissection. Four patients failed sentinel lymph node identification with SPIO. The success rate of SPIO in sentinel lymph node localization was 98.8%. Conclusion SPIO represents a feasible alternative in sentinel lymph node mapping with comparably high nodal detection rate.