Pelvic postoperative radiotherapy (external) in a dose of 6000 cGy over a 6-week period is recommended in high-risk cases such as an undifferentiated tumor, myometrial infiltration, pelvic node involvement, and in serous, clear cell and adenosquamous carcinoma. The postoperative radiotherapy is required in Stages IA (Grade 3), IA2, IB and II. Whole-abdomen radiation is required when para-aoic lymph nodes are involved while protecting the liver and kidneys.The most impoant factors in considering the need for postsurgical radiotherapy are (1) histology; (2) grading as studied by biopsy and (3) depth of myometrial invasionas seen by ultrasound, MRI and at the time of surgery.Ref: Shaw&;s textbook of gynecology; 16th edition; Page no: 512