The goal of this clinical research study is to learn if imaging (called a hysteroscopy) can be used to help guide tumor removal during a hysterectomy.

Tissue Collection and Imaging:

If participant is found to be eligible to take part in this study, during their standard-of-care hysterectomy, a tissue sample will be collected. This sample will be used for research and routine testing. Participant will sign a separate consent form for the hysterectomy.

During the hysterectomy, photographs of the tissue will be taken. Participant's private areas will be covered (as much as possible), and a picture of their face will not be taken.

A hysteroscopy will also be performed during participant's surgery. Participant's doctor will discuss the risks of the hysteroscopy with participant and they will be asked to sign a separate consent form. A hysteroscopy allows the doctor to look inside the uterus to see the tissue that is going to be collected for research imaging. This procedure is done with a tool called a hysteroscope, a long thin tube with a camera and a light. The hysteroscope will be inserted though the vagina and up into the uterus. An image will be displayed on a computer screen that is attached to the hysteroscope. The study doctor will use the image on the screen to look at different areas of the uterus to find the location and size of the tumor(s). This image may be recorded for future reference.

After the hysteroscopy, the study doctor will inject a contrast dye (Proflavine Hemisulfate) into participant's uterus to help the doctor see the lesions. A camera will then be used to photograph images of the uterus.

The tissue collection and the imaging will add about 45 minutes to participant's hysterectomy procedure.

Length of Study:

Patient's active participation in this study will be over after surgery.

Follow-Up Call:

About 30 days (+/-7 days) after the surgery, participant will be called and asked how they are doing.

This is an investigational study. The hysteroscope is commercially available and FDA approved for laparoscopic procedures. The use of the hysteroscope in this study is for research purposes only.

Proflavine Hemisulfate (contrast dye) is commercially available and FDA approved for treating umbilical cord stumps. Its use in this study is considered investigational.

Up to 20 participants will be enrolled in this study. All will take part at MD Anderson.

Inclusion Criteria:

1. Any patient with a confirmed preoperative diagnosis of endometrial cancer
2. Histologic subtype limited to endometrioid adenocarcinoma
3. Patients with any grade of endometrial cancer (histologically confirmed)
4. Patients with no contraindications to surgery
5. Patients scheduled for hysterectomy by laparotomy, laparoscopy, or robotic surgery
6. Patient must have had a preoperative MRI within 30 days of surgery at MD Anderson Cancer Center. Outside imaging will be allowed provided that staff radiologist at MD Anderson consider the quality of the study optimal to make a definitive diagnosis regarding myometrial invasion
7. Patients must have <50% myometrial invasion on preoperative MRI
8. Patients must have disease confined to either anterior or posterior wall of the uterus
9. Ability to understand and the willingness to sign a written Informed Consent Document (ICD).

Exclusion Criteria:

1. Patients with invasive uterine disease (>50% invasion) by preoperative MRI
2. Patients with a diagnosis of leiomyomata affecting the endometrium
3. Patients with a prior history of endometrial ablation
4. Patients with multifocal disease within the uterus on preoperative MRI
5. Patients with polypoid tumors protruding through the endocervical canal
6. Patients with histology other than endometrioid adenocarcinoma
7. Patients who have undergone a prior D&C for diagnosis of endometrial cancer
8. Patients with exposure to metformin within 6 months of endometrial cancer diagnosis or at the time of diagnosis
9. Patients < 18 years of age
10. Patients with a known allergy to proflavine or acriflavine
11. Patients that are pregnant or nursing