Simulation-free vaginal cuff brachytherapy for high-intermediate risk endometrial cancer.

PURPOSE: Simulation is commonly used for applicator placement verification during vaginal brachytherapy (VBT) for high-intermediate risk (HIR) endometrial cancer (EC). We evaluated vaginal recurrence (VR) outcomes in a single-institution cohort treated with VBT without simulation and compared results with those of PORTEC-4a, which mandated simulation. METHODS AND MATERIALS: We conducted a retrospective cohort study of women with HIR EC treated with VBT without simulation. VR was analyzed in a competing risks framework. Outcomes were compared with the PORTEC-4a standard brachytherapy arm. RESULTS: A total of 255 patients were included, with a median follow-up of 60.1 months. Eleven VR events were observed. The 5-year cumulative incidence of VR was 3.6% (95% CI = 1.2-6.5%). This was compared with a 5-year VR incidence of 1.6% (95% CI = 0.00-3.32%) in the PORTEC-4a standard brachytherapy arm. No significant differences in VR were observed across clinical subgroups or by applicator type. CONCLUSIONS: In this retrospective cohort meeting PORTEC-4a eligibility criteria, VBT without simulation was associated with low VR rates, comparable to those reported with simulation-verified VBT. These findings suggest that omission of simulation may not compromise vaginal control in appropriately selected patients and support further prospective evaluation of verification strategies.