French Multicenter Study Evaluating the Risk of Lymph Node Metastases in Early-Stage Endometrial Cancer: Contribution of a Risk Scoring System.

Background: This study was designed to develop a risk scoring system (RSS) for predicting lymph node (LN) metastases in patients with early-stage endometrial cancer (EC).

Methods: Data of 457 patients with early-stage EC who received primary surgical treatment between January 2001 and December 2012 were abstracted from a prospective, multicentre database (training set). A risk model based on factors impacting LN metastases was developed. To assess the discrimination of the RSS, both internal by the bootstrap approach and external validation (validation set) were adopted.

Results: Overall the LN metastasis rate was 11.8 % (54/457). LN metastases were associated with five variables: age ≥60 years, histological grade 3 and/or type 2, primary tumor diameter ≥1.5 cm, depth of myometrial invasion ≥50 %, and the positive lymphovascular space involvement status. These variables were included in the RSS and assigned scores ranging from 0 to 9. The discrimination of the RSS was 0.81 [95 % confidence interval (CI) 0.78-0.84] in the training set. The area under the curve of the receiver-operating characteristics for predicting LN metastases after internal and external validation was 0.80 (95 % CI 0.77-0.83) and 0.85 (95 % CI 0.81-0.89), respectively. A total score of 6 points corresponded to the optimal threshold of the RSS with a rate of LN metastases of 7.5 % (29/385) and 34.7 % (25/72) for low-risk (≤6 points) and high-risk patients (>6 points), respectively. At this threshold, the diagnostic accuracy was 83 %.

Conclusions: This RSS could be useful in clinical practice to determine which patients with early-stage EC should benefit from secondary surgical staging including complete lymphadenectomy.