Adjuvant radiation followed by chemotherapy is associated with improved overall survival in endometrial cancer.

Objective: Although multimodality therapy has been shown to improve outcomes for patients with high-risk endometrial carcinoma, optimal type and timing of adjuvant therapies is unknown.

Methods: Patients with stage I-IVA endometrial carcinoma diagnosed from 2004 to 2015, and treated with surgery, chemotherapy, and radiation were identified in the National Cancer Database. Adjuvant treatment was categorized as sequential radiation followed by chemotherapy (RT-CT), concurrent chemoradiation (CCRT, RT and CT started within 7 days), or sequential chemotherapy followed by radiation (CT-RT). Analysis for propensity score matched (PSM) cohorts comparing RT-CT to CCRT and CT-RT groups was additionally performed.

Results: A total of 17,070 patients were identified, including 12,402 (72.7%) treated with RT-CT, 2,153 (12.6%) with CCRT, and 2,515 (14.7%) with CT-RT. Median follow-up was 44.3 months. Five-year overall-survival (OS) by adjuvant treatment regimen was 77.3% (95% CI 76.4%-78.2%), 74.3% (95% CI 72.0%-76.3%), and 74.4% (95% CI 72.5%-76.3%), respectively (p < .001). When unmatched cohorts were stratified by stage, adjuvant RT-CT was associated with improved OS in stage I and III patients. A similar survival advantage associated with RT-CT was observed in PSM cohorts comparing RT-CT group to CCRT/CT-RT group (5-year OS 77.4% vs 74.2%, p = .001). However, the difference in OS was significant only among stage III patients (RT-CT 73.9% compared to CCRT/CT-RT 69.7%, p =.002).

Conclusion: Our findings suggest survival benefit with adjuvant RT-CT compared to CT-RT or CCRT in patients undergoing trimodality therapy for endometrial cancer. This survival benefit may be limited to stage III patients.