 Endometrial cancer is the most common gynecologic malignancy in the United States with 40,880 new cases diagnosed and 7,310 deaths attributable to this malignancy expected in 2005. The majority of patients diagnosed with endometrial cancer have early stage disease that is amenable to treatment with hysterectomy and bilateral salpingo-oophorectomy with excellent clinical outcomes. Surgical staging has improved accuracy over clinical staging for defining a low-risk population of patients who have favorable long-term outcomes with surgery alone. However, approximately 10-15 of patients with surgical stage I endometrial carcinoma confined to the uterus will have invasion to the outer one-half of the myometrium stage IC and a moderately to poorly differentiated tumor grade 2 or 3. These patients are at a higher risk for recurrence approximately 20-25 recurrence rate over 5 years. This patient population has been historically considered at intermediate-risk for recurrence because they are at lower risk than patient with disease spread beyond the uterus, but higher risk than patients with a grade 1 tumor or minimally invasive Stage IA or IB. The optimal mode of postoperative management for this population of patients has yet to be defined. 