Benefit of combination chemotherapy and radiation stratified by grade of stage IIIC endometrial cancer

•Patients with stage IIIC endometrial cancer should receive adjuvant chemoradiation.•Low-grade cancers have a survival benefit with radiation alone and chemoradiation.•High-grade cancers have a survival benefit with chemotherapy and chemoradiation. The optimal strategy for adjuvant therapy in stage IIIC endometrial cancer has not been determined. Our aim was to evaluate survival benefit of different treatments and to investigate if benefit varied by histologic grade. We identified 199 patients with stage IIIC endometrial cancer from 2000 to 2012 through the Siteman Cancer Center registry. All patients underwent surgical staging followed by no adjuvant therapy (NAT), radiation (RT), chemotherapy (CT) or chemoradiation (CRT). The association between adjuvant treatment and overall survival was explored using Kaplan-Meier plots and multivariable Cox regression analysis. Multivariable analysis was stratified by low- or high-grade to explore the interaction between grade and treatment. Most patients received CRT (50.3%) followed by CT (23.1%), RT (16.1%) and NAT (10.5%). Survival after CRT was superior to NAT (p