Inclusion Criteria:  Endometrial adenocarcinoma is confirmed by pathology, and the molecular types were microsatellite instability type and low copy type; Stage IA and grade 3 or stage IB (FIGO 2009), without substantial lymph-vascular space invasion; Surgery must have included a hysterectomy and bilateral adnexectomy. Pelvic lymph node sampling and para-aortic lymph node sampling are optional; ECOG score is 0-2; The interval time between surgery and radiotherapy is no more than 8 weeks; The routine blood examination was normal; Compliance is good and informed consent is voluntarily signed.  Exclusion Criteria:  The patients receive chemotherapy; History of previous malignant disease; Previous diagnosis of Crohn's disease or ulcerative colitis.