To compare the effect of vaginal brachytherapy as adjuvant treatment after operation when compared to pelvic external beam radiotherapy in patients with early endometrial cancer based on moderate risk molecules classification.

After being informed the study and potential risk，all patients giving written informed consent will be undergo a 1-week screening period determine eligibility for study entry. At week 0, patients who meet the eligibility will be randomized in a 1:1 ratio to vaginal brachytherapy or pelvic external beam radiotherapy. After treatment, patients were followed up regularly.

Inclusion Criteria:

1. Endometrial adenocarcinoma is confirmed by pathology, and the molecular types were microsatellite instability type and low copy type;
2. Stage IA and grade 3 or stage IB (FIGO 2009), without substantial lymph-vascular space invasion;
3. Surgery must have included a hysterectomy and bilateral adnexectomy. Pelvic lymph node sampling and para-aortic lymph node sampling are optional;
4. ECOG score is 0-2;
5. The interval time between surgery and radiotherapy is no more than 8 weeks;
6. The routine blood examination was normal;
7. Compliance is good and informed consent is voluntarily signed.

Exclusion Criteria:

1. The patients receive chemotherapy;
2. History of previous malignant disease;
3. Previous diagnosis of Crohn's disease or ulcerative colitis.