Observational Study of Women With Endometrial Cancer Who Receive the Standard Treatment for Their Disease

This study is being done to find out how often endometrial cancer recurs after the standard treatment as well as how often the standard treatment results in a lymphedema.

Screening Inclusion Criteria: * ECOG performance status 0-1 or KPS ≥ 70% * Age ≥ 18 years * Endometrioid adenocarcinoma histologic diagnosis on endometrial biopsy or dilatation and curettage * No evidence of extrauterine disease, or suspicious pelvic lymph nodes, or distant metastases, or cervical invasion on pre-operative conventional imaging studies (Pelvic +/- Abdomen CT or MRI or sonogram, or body PET scan) and physical examination (uterine confined by exam and imaging ) * Suitable candidate for surgery * Planned surgical treatment including hysterectomy in combination with SLN biopsy and a bilateral salpingo-oophorectomy * No history of second primary cancer (invasive or in situ) within the past 5 years, not including non-melanoma skin cancer * Approved and signed informed consent * No history of neoadjuvant chemotherapy or radiotherapy for endometrial cancer * No history of prior pelvic or abdominal radiotherapy Screening Exclusion Criteria: * Extrauterine disease, or gross lymph node involvement, or cervical invasion suspected on pre-operative imaging studies and physical examination (disease not uterine confined clinical stage \> I) * Contraindication for SLN mapping * The planned treatment is not surgery, or the surgical treatment does not include hysterectomy in combination with SLN biopsy and a bilateral salpingo-oophorectomy Eligibility Inclusion Criteria Patients will be classified in the study cohort (part 2; n=182) according to surgical treatment received, final post hysterectomy and staging pathologic report, and planned adjuvant treatment. The inclusion criteria are specified below. Study Cohort (n=182) A patient will be enrolled in the study cohort if all the following criteria are met: * At surgery, the patient must undergo: * Hysterectomy * Bilateral salpingo-oophorectomy, unless already performed (including allowing unilateral salpingo-oophorectomy if unilateral salpingo-oophorectomy already performed) * Bilateral pelvic SLN mapping (bilateral sentinel nodes are negative for malignancy) * On the final pathologic report, the patient must have a diagnosis of: * Stage I intermediate-risk endometrial endometrioid cancer (Grade 1 or Grade 2 with ≥ 50% myometrial invasion or Grade 3 with \