Objective:The present study was designed to evaluate the effects of adjuvant chemotherapy(CT)vs.radiotherapy(RT,alone or combined with CT)on the prognosis of patients with high-risk,early-stage(stage Ⅰ and stage Ⅱ)endometrioid endometrial carcinoma.Methods:This single-center retrospective clinical study was conducted in Union Hospital,Tongji Medical College,Huazhong University of Science and Technology between 2010 and 2019.In the present study,endometrioid endometrial carcinoma patients,who underwent total hysterectomy and bilateral salpingo-oophorectomy followed by postoperative adjuvant CT or RT(alone or combined with CT),and were diagnosed with stage IA grade 2/3 with lymph-vascular space invasion(LVSI),and stage IB with two or more uterine risks,including old age,histological grade 2 or 3,LVSI and stage Ⅱ,were included.According to the postoperative adjuvant therapy,all eligible patients were divided into two groups:CT group and RT(RT±CT)group.The primary objective was to investigate overall survival(OS)and disease-free survival(DFS)between the CT and RT groups.Grade 3 or worse adverse events were also presented in the present study.Results:A total of 145 eligible patients were included.Among these patients,97 patients underwent adjuvant CT and 48 patients underwent adjuvant RT(RT±CT).The median follow-up was 47.2 months,and the five-year OS rate was 92.7％in the CT group and 88.6％in the RT group[hazard ratio(HR):0.81,95％confidence interval(CI):0.22-2.99).The 5-year DFS rate for the two groups was 85.7％and 80.2％,respectively(HR:0.82,95％CI:0.33-2.05).The cumulative incidence of local-regional disease recurrence at 60 months of follow-up was 6.2％in the CT group and 6.3％in the RT group(HR=1.11;95％CI:0.28-4.35).The cumulative incidence of distant recurrence at 60 months of follow-up was 5.2％in the CT group and 10.4％in the RT group(HR=0.65;95％CI:0.19-2.24).Both groups of patients were well-tolerant,and the only grade 3 or worse adverse events were neutropenia and thrombocytopenia.Conclusion:There was no difference in efficacy for adjuvant CT or adjuvant RT(RT±CT)in high-risk,early-stage endometrioid endometrial carcinoma.CT exhibited a trend of reducing the distant relapse,although there was no significant difference,when compared with adjuvant RT(RT±CT).