The Number of Sentinel Lymph Nodes Could be Optimized by Adjusting the Injection Dose

Background: The optimal number of sentinel lymph nodes (SLNs) to beremoved is controversial based on the false negative rate and prognosis. Weinvestigated factors related to the number of SLNs and the possibility ofoptimizing the number of SLNs.Methods: We retrospectively reviewed 167 cases in which 0.3 or 0.5 ml offerucarbotran was sub-dermally injected without massage from July 2016 toNovember 2018. Sentinel lymph node biopsy (SNB) was conducted using bothradioisotope (RI) and superparamagnetic iron oxide (SPIO). The removed nodeswith a value of ≥0.5 μT on a magnetometer were considered to be SLNs (SPIOnodes). The total SPIO node count in each case was calculated.Results: There was a significant correlation between the number of SPIOnodes and total count of SPIO nodes (rs=0.821, p<0.0001). With RI and SPIOmethods, the average number of removed nodes in the age≥75 years and BMI≥25subgroups was significantly lower than that in the age<75 years and BMI<25subgroups. The number of SPIO nodes was significantly influenced by the injecteddose. The average number of SPIO nodes in the age ≥75 years and BMI≥25subgroups after injection of 0.5 ml was almost the same as that of the age <75 yearsand BMI<25 subgroups after injection of 0.3 ml.Conclusion: Obesity and old age seemed to be associated with slow lymphaticflow; however, increasing the dose increased the number of SPIO nodes. Thus,optimization of the number of SLNs seems possible.

The Number of Sentinel Lymph Nodes Could be Optimized by Adjusting the Injection Dose Keywords:

Sentinel node biopsy , superparamagnetic iron oxide nanoparticles (SPIO) , neodymium magnet , magnetometer