Background Growing evidence suggest that sentinel lymph node (SLN) biopsy in endometrial cancer accurately detects lymph node metastasis. However, prospective randomized trials addressing the oncological outcomes of SLN biopsy in endometrial cancer without lymphadenectomy are lacking.

Primary Objectives The present study aims to confirm that SLN biopsy without systematic node dissection does not negatively impact oncological outcomes.

Study Hypothesis We hypothesized that there is no survival benefit in adding systematic lymphadenectomy to sentinel node mapping for endometrial cancer staging. Additionally, we aim to evaluate morbidity and impact in quality of life (QoL) after forgoing systematic lymphadenectomy.

Trial Design This is a collaborative, multicenter, open-label, non-inferiority, randomized trial. After total hysterectomy, bilateral salpingo-oophorectomy and SLN biopsy, patients will be randomized (1:1) into: (a) no further lymph node dissection or (b) systematic pelvic and para-aortic lymphadenectomy.

Major Inclusion and Exclusion Criteria Inclusion criteria are patients with high-grade histologies (endometrioid G3, serous, clear cell, and carcinosarcoma), endometrioid G1 or G2 with imaging concerning for myometrial invasion of ≥50% or cervical invasion, clinically suitable to undergo systematic lymphadenectomy.

Primary Endpoint(s) The primary objective is to compare 3-year disease-free survival and the secondary objectives are 5-year overall survival, morbidity, incidence of lower limb lymphedema, and QoL after SLN mapping ± systematic lymphadenectomy in high-intermediate and high-risk endometrial cancer.

Sample size 178 participants will be randomized in this study with an estimated date for completing accrual of December 2024 and presenting results in 2027.

Trial Registration Number NCT03366051.