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

Screening Inclusion Criteria:

• ECOG performance status 0-1 or KPS ≥ 70%

• Age ≥ 18 years

• Endometrioid adenocarcinoma histologic diagnosis on endometrial biopsy or dilatationand curettage

• No evidence of extrauterine disease, or suspicious pelvic lymph nodes, or distantmetastases, or cervical invasion on pre-operative conventional imaging studies (Pelvic +/- Abdomen CT or MRI or sonogram, or body PET scan) and physicalexamination (uterine confined by exam and imaging )

• Suitable candidate for surgery

• Planned surgical treatment including hysterectomy in combination with SLN biopsy anda 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 invasionsuspected on pre-operative imaging studies and physical examination (disease notuterine confined clinical stage > I)

• Contraindication for SLN mapping

• The planned treatment is not surgery, or the surgical treatment does not includehysterectomy 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 allowingunilateral salpingo-oophorectomy if unilateral salpingo-oophorectomy alreadyperformed)

• Bilateral pelvic SLN mapping (bilateral sentinel nodes are negative formalignancy)

• On the final pathologic report, the patient must have a diagnosis of:

• Stage I intermediate-risk endometrial endometrioid cancer (Grade 1 or Grade 2with ≥ 50% myometrial invasion or Grade 3 with <50% myometrial invasion,including non-invasive disease)

• Negative pelvic peritoneal cytology

• Adjuvant treatment as recommended by the multidisciplinary team must be as follows:

• No adjuvant treatment, or

• Intravaginal radiation only

Eligibility Exclusion Criteria

• There is intra-operative detection of extra-uterine disease or grossly involvedlymph nodes

• Presence of any positive pelvic nodes including micrometastasis and isolated tumorcells (ITC)

• Hysterectomy is not performed

• Bilateral salpingo-oophorectomy is not performed, unless already performed (unilateral salpingo-oophorectomy is allowed if unilateral salpingo-oophorectomyalready performed)

• Failed unilateral or bilateral SLN mapping

• Patient undergoes a complete unilateral or bilateral pelvic lymphadenectomy

• Patient undergoes a radical type C hysterectomy

• Stage IA endometrioid cancer Grade1 or 2 and myometrial invasion <50%

• Stage IB Grade 3 endometrioid cancer

• Non-endometrioid histology: Serous, clear cell, carcinosarcoma, undifferentiated, orde-differentiated histology noted on final hysterectomy pathology

• Empty unilateral or bilateral sentinel lymph nodal packet(s)

• Positive peritoneal cytology