American GOG classifies endometrial cancer into: low risk of recurrence (low risk): stage IA, IB and G1 or G2; moderate risk of recurrence (moderate risk): G3, IC, stage II; high risk of recurrence (high risk): stage III and above; moderate risk and high risk all require postoperative adjuvant radiotherapy, while low risk does not require radiotherapy. The scope of radiotherapy can only be in the pelvic cavity or a slightly higher plane. Most of the metastases of endometrial cancer are in the pelvic cavity, but a few endometrial cancers metastasize directly to the lymph nodes adjacent to the abdominal aorta, which cannot be covered by radiotherapy and have poor efficacy.