Clinical Significance of Discordances in Sentinel Lymph Node Reactivity Between Radioisotope and Indocyanine Green Fluorescence in Patients With cN0 Breast Cancer Patients

Abstract Background: To evaluate the usefulness of combining radioisotopes and indocyanine green (ICG) and investigate discordances in sentinel lymph node (SN) reactivity using each tracer in cN0 breast cancer patients.Methods: 338 cN0 primary breast cancer patients who underwent SN biopsy with radioisotopes and ICG and axillary lymph node (ALN) dissection were included. SN positivities with radioisotopes, ICG, and both were denoted as SN(RI), SN(ICG), and SN(RI+ICG), respectively. We retrospectively estimated metastatic SN detection rates, each method’s discordance rate, and correlation of discordances in SN reactivity with postoperative N staging.Results: The combination of radioisotopes and ICG had higher metastatic SN detection rates (99.7%) than radioisotopes or ICG alone (91.7% and 96.4%, respectively; p<0.01). The discordance rate between SN(RI) (11 cases) and SN(ICG) (27 cases) in detecting metastatic SNs was 11.2%. The absence of SN(RI), cT stage (cT2-3), higher histological grade, and histological type were identified as risk factors of pN2-3 disease (odds ratios: 8.64, 2.56, 1.92, and 3.28, respectively; p<0.01).Conclusions: Discordances in SN reactivity between radioisotopes and ICG helps identify SN metastasis. Although the absence of SN(RI) is rare, it is a significant sign of advanced ALN metastases; ALN dissection should be considered for accurate nodal staging.