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.