Frozen Section for Detection of Lymph Nodes After Cervical Injection with Indocyanine Green (ICG) for Sentinel Lymph Node Technique in Endometrial Cancer Staging

Objective: The aim of this study was to assess the role of frozen section (FS) in identifying an absence of lymph nodes during sentinel lymph node (SLN) biopsy for apparent early-stage endometrial cancer (EC). Methods: Consecutive apparent early-stage EC patients who had SLNs removed after cervical injection with indocyanine green (ICG) from 1 June 2014 to 30 June 2016 were analyzed. An empty node (EN) was defined as an SLN specimen without evidence of lymph node(s). The association of tumor and patient characteristics with an EN was evaluated, and trend analysis to compare the rate of ENs over calendar quarters was performed. A decision-tree model was then created to compare the use of FS versus no FS for SLN evaluation in the hypothetical cohort affected by early-stage EC in the US each year. Results: Over the study period, 300 patients met the inclusion criteria. FS revealed ENs in 24 (8%) patients. No association between patient demographic characteristics (age, body mass index, prior abdominopelvic surgery, international federation of gynecology and obstetrics (FIGO) stage, histology, myometrial invasion, cervical stromal invasion) and presence of ENs was observed. The rate of ENs at FS did not change over time (p = 0.68). The hypothetical analysis showed a 4.3% decrease of inappropriately staged patients with the use of FS on the SLN (95% confidence interval 4.1–4.5). Conclusions: ENs during SLN biopsy for EC staging is not a rare event and can be easily detected with FS. The implementation of FS of SLN might reduce inadequate staging of EC. Individual institutions may want to examine their own EN rates and determine if this would assist them in their SLN practices for EC.