Outcomes of low-risk endometrial cancer with isolated tumor cells in the sentinel lymph nodes: a prospective, multi-center, single-arm, observational study (ENDO-ITC study)

Abstract

Background: It is unclear whether isolated tumor cells (ITCs) in sentinel lymph nodes (SLNs) adversely affect prognosis, especially in low-risk endometrial cancer. In a retrospective study, we showed a worse recurrence-free survival for low-risk endometrial cancer with ITCs than the node-negative group.

Primary objective: Our aim is to evaluate whether the likelihood of disease recurrence differs between a prospective cohort of patients with low-risk endometrial cancer with ITCs and an historical cohort with negative SLNs.

Study hypothesis: We hypothesize that patients with low-risk endometrial cancer and ITCs will have a worse recurrence-free survival than patients who are node-negative.

Trial design: This is a prospective, multi-center, single-arm observational study. Consecutive patients with low-risk endometrial cancer with ITCs in the SLNs will be accrued. Observation only will be suggested after surgery.

Major inclusion/exclusion criteria: We will include patients with endometrial cancer undergoing pelvic SLN biopsy and ultra-staging with the following characteristics: endometrioid histology, grades 1 to 2, <50% myometrial invasion, without substantial/extensive lympho-vascular space invasion. ITCs in SLNs are defined as tumor cell aggregates ≤0.2 mm or <200 cells.

Primary end point: The primary end point is recurrence-free survival, measured from the date of surgery to the date of recurrence, death, or last disease evaluation.

Sample size: With a sample size of 132 women with low-risk endometrial cancer and ITCs, a 1-sided log-rank test achieves 85% power at a 0.05 significance level to detect an HR of 2.1. The expected number of events during the study is 17.3.

Estimated dates for completing accrual and presenting results: The study duration will be 60 months: 24 for enrollment and 36 for follow-up. The results are expected in 2029.

Trial registration: ClinicalTrials.gov: NCT06689956.

Keywords: Endometrial Cancer; Isolated Tumor Cells; Sentinel Lymph Nodes.