Introduction The status of regional node remains one of the most important factors to guide adjuvant therapy in endometrial cancer (EC). Pelvic recurrence occurs in up to 15% of early EC patients with negative pelvic lymph nodes (LNs). The prognostic significance of detecting micrometastases (μM) in LN is debated. This retrospective case-control study performed in the Oncological Gynecology Department in Lyon between December 1998 and June 2012 reports the incidence and the clinical significance of μM detected during ultrastaging of negative sentinel lymph node (SLN) in EC.

Patients and Methods Ninety-three patients affected by type I and II EC were submitted to surgery with SLN. Dual-labeling method was used to detect SLN. All the SLNs were subjected to ultrastaging researching μM. The patients with a locoregional or distant relapse represented the case-series (CS). The patients without locoregional or distant recurrences were the case-controls (CC).They were matched (1:2 ratio) according to age, International Federation of Gynecology and Obstetrics stage, and histopathologic features.

Results Ten patients presenting a relapse represented CS. In the remaining 83 patients without recurrence, 20 CC were individualized. The detection rate of SLN per hemipelvis was of 17 (85%) of 20 hemipelvis and of 33 (82.5%) of 40 hemipelvis for CS and CC, respectively. Two SLN of CS arm were positives at frozen section. One of the 8 patients of CS arm with negative SLNs was positive for μM by immunohistochemistry analysis.

Conclusions Lymph node status is one of the most important histopathologic features to determine the adjuvant treatment. The SLN technique could be proposed in selected patients affected by early EC. The μM in SLN could be researched and could help to modulate the following treatment. The multicenter study must be performed to clarify the optimal method of research of SLN in EC and the significance of μM in the LN.