OUTLINE: This is a randomized, multicenter study. Patients are stratified according to center, tumor histology (leiomyosarcoma vs mixed mesodermal sarcoma vs endometrial stromal sarcoma), and surgical procedure (total abdominal hysterectomy (TAH) with or without bilateral salpingo-oophorectomy (BSO) vs TAH and BSO with pelvic and para-aortic node sampling and random biopsies). Patients are randomized to 1 of 2 treatment arms. Arm I: Beginning within 6 weeks after surgery, patients undergo pelvic radiotherapy 5 days a week for 5.6 weeks. Arm II: Patients undergo observation alone. Patients are followed every 2 months for 1 year, every 3 months for 2 years, and then every 6 months thereafter.