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

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.