Pelvic Radiation Therapy or Vaginal Implant Radiation Therapy, Paclitaxel, and Carboplatin in Treating Patients With High-Risk Stage I or Stage II Endometrial Cancer

PRIMARY OBJECTIVES: I. To determine if treatment with vaginal cuff brachytherapy followed by three cycles of chemotherapy reduces the rate of recurrence or death (i.e. increases recurrence-free survival) when compared to pelvic radiation therapy. SECONDARY OBJECTIVES: I. To compare survival between the two treatment groups. II. To compare patterns of failure between the two treatment groups. III. To compare physical functioning, fatigue and neurotoxicity between the two treatment groups. IV. To examine associations between primary comorbid illnesses and obesity on survival, fatigue and physical functioning. V. To evaluate the psychometric properties (such as construct validity, reliability, sensitivity to treatment and responsiveness over time) of the Patient-Reported-Outcomes Measurement Information System (PROMIS) Fatigue Short form 1, and to evaluate fatigue measurement equivalence between women with endometrial cancer and age-matched women from the general United States (US) population. TERTIARY OBJECTIVES: I. To evaluate the ability of gene expression signatures in early stage endometrial cancer to predict recurrence and to explore the association between gene expression signatures in early stage endometrial cancer and clinical characteristics and outcome. II. To bank whole blood specimens for future research. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients undergo conventional or intensity-modulated pelvic radiation therapy once daily, 5 days a week, for 5-6 weeks (total of 25-28 fractions) in the absence of disease progression or unacceptable toxicity. Patients with stage II disease or stage I disease with a confirmed diagnosis of clear cell and/or papillary serous histology may also undergo 1 or 2 intravaginal (i.e., vaginal cuff) brachytherapy boost treatments. ARM II: Patients undergo vaginal cuff brachytherapy comprising 3-5 high-dose rate brachytherapy treatments over approximately 2 weeks or 1 or 2 low-dose rate brachytherapy treatments over 1-2 days. Beginning within 3 weeks after initiating brachytherapy, patients receive paclitaxel intravenously (IV) over 3 hours and carboplatin IV over 30-60 minutes on day 1. Chemotherapy repeats every 21 days for up to 3 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 2 years, every 6 months for 3 years, and then annually thereafter for up to 5 years.