Background The intrauterine manipulator used during a hysterectomy for endometrial cancer has been suggested as a reason for worsening oncologic outcomes. However, only a few non-randomized retrospective studies have investigated this association.

Primary Objective(s) To compare 4-year recurrence-free survival in the group of patients who undergo hysterectomy using an intrauterine manipulator with that of those who undergo hysterectomy without it.

Study Hypothesis Patients with endometrial cancer who undergo laparoscopic hysterectomy performed with an intrauterine manipulator would have a lower recurrence-free survival than patients who undergo laparoscopic hysterectomy without a manipulator.

Trial Design Multicenter, parallel arm, open-label, randomized controlled trial.

Major Inclusion/Exclusion Criteria Adult women diagnosed with apparently uterine-confined endometrial cancer of any histology are eligible. We exclude women who had synchronous or previous (<5 years) invasive cancer, had a WHO performance score >2, and had inadequate baseline organ function.

Primary Endpoint(s) 4-Year recurrence-free survival defined as any relapse or death related to endometrial cancer or treatment calculated from randomization to the date of the first recurrence-free survival event.

Sample Size With an accrual time of 4 years, a minimum follow-up length of 4 years, and a two-sided type I error of 0.05, we need to enroll 515 women per arm to have a statistical power of 80% to reject the null hypothesis (HR for recurrence=1), assuming that patients who undergo hysterectomy with the use of the intrauterine manipulator have a 3-year recurrence rate of 12.5% and without the use of the intrauterine manipulator of 8.5% (HR for recurrence=1.50), and that 5% of patients are lost at follow-up in each arm, with a median time of 24 months.

Estimated Dates for Completing Accrual and Presenting Results Accrual completion is expected in 2028, and result presentation in 2032.

Trial Registration ClinicalTrial.gov ID NCT05687084.