A Randomized Phase III Trial of Two Standard Dose Fractionation Regimes for Adjuvant Vaginal Brachytherapy in Early Stage Endometrial Cancer

Inclusion Criteria: * Willingness and ability to provide written informed consent and to comply with the study protocol as judged by the investigator. * Surgery consisted of Total Abdominal or Laparoscopic Hysterectomy and Bilateral Salpingo Oophorectomy (TH-BSO) with or without lymph node dissection. * Subject must have FIGO Stage I-II (grade 1-3) pathologically proven (histologic) endometrioid cancer, including all subtypes. Serous, clear cell, and carcinosarcoma histologic pathologies are allowed. * Subjects must have no measurable disease after surgery. * ECOG Performance Status of 0-2 * Age ≥ 18 years * Subject must have a life expectancy ≥ 12 months Exclusion Criteria: * Disease of more advanced stage (FIGO stage III-IV) or disease for which adjuvant external beam radiation therapy or chemotherapy is indicated * Patients with a history of prior pelvic radiation therapy or if additional pelvic radiation therapy is planned * Subjects who have not recovered from side effects of agents administered more than 4 weeks prior to the on-study date * Subjects that require \> 14 weeks between surgery and initiation of radiation therapy on study unless the subject is receiving chemotherapy. Subjects receiving chemotherapy may have radiation therapy initiated within 6 months after surgery. \* Subjects who do not meet this criteria may still be eligible. The UVA Coordinating Center and Overall Study PI will review each case and inform the site of the approval decision. * Subjects who are receiving any investigational agents or have had any investigational agent within the 30 days prior to the on-study date * Subject is unable or unwilling to participate in a study-related procedure * Pregnant and breastfeeding women are excluded from this study * Subject is a prisoner * A serious uncontrolled medical disorder that in the opinion of the Investigator would impair the ability of the subject to receive protocol therapy. * Subjects with a history of evidence upon physical examination of central nervous system disease including primary brain tumor, seizures not controlled with standard medical therapy, any brain metastases, or history of cerebrovascular accident (stroke), transient ischemic attack, or subarachnoid hemorrhage within six months of study entry