Inclusion Criteria:

• 1. Surgery must have included a hysterectomy. Bilateral salpingo-oophorectomy, pelvic lymph node sampling, para-aortic lymph node sampling, and omentectomy are optional
• 2. Patients will be staged according to FIGO 2009 staging system. Eligibility is defined based on clinical-pathologic features.
• 3. Patients with endometrioid endometrial cancer with the following:
• * Stage IA grade 3 with extensive LVSI
• * Stage IB grade 3
• * Stage II
• * Stage III (A, B, and C)
• * Stage IVA who are recommended adjuvant whole pelvic RT (+/- lower para-aortic up to renal hilum) and systemic chemotherapy.
• 4. Patients with clear cell, serous papillary carcinoma, or carcinosarcoma with stages IA-III who are recommended adjuvant whole pelvic RT (+/- lower para-aortic up to renal hilum) and systemic chemotherapy.
• 5. Patients with a GOG Performance Status of 0, 1, or 2
• 6. Patients with adequate organ function, reflected by the following parameters:
• * WBC ≥ 3000/mcl
• * Absolute neutrophil count (ANC) ≥ 1000/mcl
• * Platelet count ≥ 100,000/mcl
• * SGOT, SGPT, and alkaline phosphatase ≤ 2.5 X upper limit of normal (ULN)
• * Bilirubin ≤ 1.5 X ULN
• * Creatinine ≤ institutional ULN (if serum creatinine \> ULN, estimated GFR ≥ 45 ml/min)
• 7. Patients who have signed an approved informed consent and authorization permitting release of personal health information
• 8. Patients must be 18 years of age or older

Exclusion Criteria:

• 1. Patients with leiomyosarcoma
• 2. Patients with clinically significant pelvic or para-aortic nodal disease, on post-surgery CT scan, that was not dissected and would require higher boost dose
• 3. Patients with recurrent endometrial cancer with gross nodal or vaginal disease requiring high dose radiotherapy, or history of prior chemotherapy
• 4. Patients with a history of prior pelvic/abdominal RT or with history of prior cancer treatment that contraindicates this protocol therapy including history of prior chemotherapy for any other malignancy.
• 5. Patients with a history of serious co-morbid illness or uncontrolled illnesses that would preclude protocol therapy
• 6. Patients with an estimated survival of less than three months
• 7. Patients with FIGO 2009 Stage IVB endometrial cancer
• 8. Patients with a history of myocardial infarction, unstable angina, or uncontrolled arrhythmia within 3 months from enrollment