Radiation or Observation Only in Endometrial Cancer Who Have Undergone Surgery

OBJECTIVES: * Compare the overall survival in patients with intermediate-risk endometrial cancer treated with pelvic radiotherapy vs observation after laparoscopically-assisted vaginal hysterectomy or total abdominal hysterectomy and bilateral salpingo-oophorectomy. * Compare the time to locoregional recurrence (i.e., in the vaginal mucosa or elsewhere in the central pelvic area or lateral pelvic walls) in patients treated with these regimens. * Compare the duration of ultimate pelvic control and event-free survival in patients treated with these regimens. * Compare the toxic effects of these regimens in these patients. * Compare the quality of life of patients treated with these regimens. * Compare sexual health issues in patients treated with these regimens. OUTLINE: This is a randomized, multicenter study. Patients are stratified by center, tumor grade (1 vs 2 vs 3), surgical staging (yes vs no), and sexual health assessment (yes vs no). Patients undergo laparoscopic-assisted vaginal hysterectomy or total abdominal hysterectomy and bilateral salpingo-oophorectomy. After surgery, patients are randomized to 1 of 2 treatment arms. * Arm I: Patients undergo observation alone. * Arm II: Beginning within 12 weeks (preferably within 6-8 weeks) after surgery, patients undergo radiotherapy 5 days a week for 5 weeks in the absence of disease progression or unacceptable toxicity. Protocol-defined brachytherapy is allowed. Quality of life is assessed at baseline; at 16-18 weeks after surgery (arm I) or 5 and 9 weeks after initiating radiotherapy (arm II); and then at 6, 12, 18, 24, 36, 48, and 60 months. Patients are followed every 3 months for 2 years, every 4 months for 1 year, every 6 months for 2 years, and then annually thereafter. PROJECTED ACCRUAL: A total of 400 patients will be accrued for this study.