Tips and tricks to improve sentinel lymph node mapping with Indocyanin green in endometrial cancer

To determine the validity of sentinel lymph node (SLN) biopsy with ICG in endometrial cancer and to evaluate the factors associated with poor mapping or false negative.

We reviewed all patients who underwent primary surgery for endometrial carcinoma with SLN mapping using ICG followed by pelvic lymphadenectomy from February 2014 to December 2015. SLNs were ultrastaged on final pathology. Patients' demographics, surgical approach and histopathological factors were prospectively collected. Detection rate, sensitivity and negative predictive value (NPV) were calculated and univariate analysis was performed to evaluate factors associated with failed bilateral detection of SLNs.

A total of 119 patients were included. The overall and bilateral detection rates were 93% and 74%. Sensitivity and NPV were 100% in patients with bilateral detection; 95% and 99% respectively in cases with at least unilateral detection. Advanced FIGO stage (III or IV) was the only factor related to failed bilateral detection (p = 0.01). In 14 hemi-pelvis, the specimen labelled as SLN did not contain nodal tissue on final pathology (only lymphatic channels), which represented 37% of the "failed detection" cases. One false negative occurred in a patient with an ipsilateral clinically suspicious enlarged lymph node.

ICG is an excellent tracer for SLN mapping in endometrial cancer. Advanced FIGO stage correlated with failed bilateral detection (p = 0.01). Suspicious lymph nodes should be removed regardless of the mapping. Care should be taken to ensure that SLN specimen actually contains nodal tissue and not only swollen lymphatic channels, as this represents a significant cause of failed SLN mapping.