Sentinel lymph node mapping with pathologic ultrastaging: A valuable tool for assessing nodal metastasis in low-grade endometrial cancer with superficial myoinvasion

•SLN mapping with ultrastaging can detect microscopic nodal disease.•Pathologic ultrastaging may not be necessary in uterine tumors without myoinvasion.

ObjectiveTo report the incidence of nodal metastases in patients presenting with presumed low-grade endometrioid adenocarcinomas using a sentinel lymph node (SLN) mapping protocol including pathologic ultrastaging.MethodsAll patients from 9/2005 to 12/2011 who underwent endometrial cancer staging surgery with attempted SLN mapping for preoperative grade 1 (G1) or grade 2 (G2) tumors with < 50% invasion on final pathology, were included. All lymph nodes were examined with hematoxylin and eosin (H&E). Negative SLNs were further examined using an ultrastaging protocol to detect micrometastases and isolated tumor cells.ResultsOf 425 patients, lymph node metastasis was found in 25 patients (5.9%) on final pathology—13 cases on routine H&E, 12 cases after ultrastaging. Patients whose tumors had a DMI < 50% were more likely to have positive SLNs on routine H&E (p < 0.005) or after ultrastaging (p = 0.01) compared to those without myoinvasion.ConclusionsApplying a standardized SLN mapping algorithm with ultrastaging allows for the detection of nodal disease in a presumably low-risk group of patients who in some practices may not undergo any nodal evaluation. Ultrastaging of SLNs can likely be eliminated in endometrioid adenocarcinoma with no myoinvasion. The long-term clinical significance of ultrastage-detected nodal disease requires further investigation as recurrences were noted in some of these cases.