Anatomic Asymmetry in Sentinel Lymph Node Detection in Endometrial Cancer

Study Objective: To determine whether the concomitant use of indocyanine green (ICG) with technetium-99m–filtered sulfur colloid (Tc99m-FSC) improves bilateral sentinel lymph node (SLN) detection rate in endometrial cancer and whether anatomic concordance of pelvic lymph nodes exists and can be used to predict SLN location in cases of unilateral mapping failure. Design: Retrospective cohort study. Setting: Tertiary academic medical center in Holon, Israel. Patients: Patients diagnosed with endometrial cancer, who underwent SLN mapping with Tc99m-FSC, ICG, or both, at our center between 2014 and 2019. Interventions: A total of 111 patients were included in the study. SLN mapping using Tc99m-FSC was performed in 101 (91.9%) patients, and ICG injection was given to 64 (57.6%) patients of whom 55 (49.5%) received both. We compared SLN detection rates (unilateral and bilateral) and anatomic symmetry for each method alone and for a combination of the 2. Measurements and Main Results: The overall detection rate for unilateral SLNs was 96.4%; 96.9% with ICG, 93.1% with gamma-probe, and 98.2% by combining both methods. The total bilateral detection rate was 72.1%, with ICG performing better as a single tracer than Tc99m-FSC (75% vs 63.4%, respectively). In 55 women in whom both tracers were used, the bilateral detection rate was significantly higher compared with Tc99m-FSC alone. Symmetric pelvic anatomic concordance of SLN was found in only 35 of 80 patients with bilateral SLN detection (43.8%). Conclusion: The combination of preoperative radioisotope injection and intraoperative ICG administration may yield the best bilateral SLN detection rate. In cases of unilateral mapping failure, one cannot rely on the anatomic location of the ipsilateral SLN detected to harvest the complementary node because the symmetric concordance is poor.