AbstractObjectivesTo explore the survival and definition of stage IA mixed endometrial carcinoma.MethodsFrom June 1, 2010, to June 1, 2017, cases with stage IA endometrial cancer were included in this study. The survival outcomes were compared among patients with endometrioid (group A), nonendometrioid (group B), and mixed subtypes (group C) and among patients with different proportions of nonendometrioid components (<5%, >50%, and others).ResultsIn total, 890 cases were included, comprising 808 (90.8%), 33 (3.7%), and 47 (5.3%) cases in groups A, B, and C, respectively. After a median follow-up of 55.9 months, groups B and C had significantly more inferior disease-free survival, overall survival, and cancer-specific overall survival. Patients with a nonendometrioid proportion of more than 50% and serous subtype also had a significantly more inferior prognosis. Adjuvant therapy could improve the prognosis in mixed endometrial carcinomas.ConclusionsPatients with endometrial cancer of mixed subtypes had inferior survival outcomes.