The goal of this observational study is to evaluate the accuracy of a novel molecular test for screening and monitoring endometrial lesions in women at medium-to-high risk for endometrial cancer.

The main questions it aims to answer are:

• What is the sensitivity and specificity of the CISENDO test (a DNA methylation test on cervical cytology samples) for detecting histologically confirmed endometrial intraepithelial neoplasia (EIN) or invasive endometrial cancer?
• How do DNA methylation levels change during the follow-up of endometrial lesions? Researchers will compare the results of the CISENDO test to the results from the standard diagnostic procedure (hysteroscopy with histology) to see if the molecular test can reliably identify high-risk lesions and track disease progression.

Participants will:

• Provide a residual liquid-based cervical cytology sample for the CISENDO test.
• Undergo a standard diagnostic hysteroscopy examination (with or without biopsy) for comparison.
• Some participants will return for follow-up visits at 6 and 12 months for repeat methylation testing and/or hysteroscopy to monitor their condition.

Inclusion Criteria:

1. Participants must be 18 years of age or older.
2. Participants must possess medium-to-high risk factors for endometrial cancer as defined by Chinese consensus guidelines and are scheduled for hysteroscopic evaluation; OR are currently undergoing conservative treatment (e.g., progesterone therapy or endometrial ablation) for endometrial lesions, and have not received chemotherapy.
3. Participants must be capable and willing to provide written informed consent.
4. Participants must be willing to undergo at least one follow-up assessment within 1 year.
5. Participants must have an intact cervix (a history of LEEP or conization is acceptable).

Exclusion Criteria:

1. Current treatment for any gynecologic malignancy other than endometrial cancer.
2. Current or untreated cervical, vaginal, or vulvar intraepithelial neoplasia or carcinoma.
3. History of total or subtotal hysterectomy, trachelectomy, radical trachelectomy, or pelvic radiotherapy.
4. Active lower genital tract bleeding.
5. Immunosuppressed state (e.g., HIV infection, status post organ transplantation).
6. Failure to undergo the planned hysteroscopic evaluation and follow-up within 1 year after the initial assessment.
7. Failed hysteroscopic procedure.
8. Any other condition that, in the opinion of the investigator, makes the participant unsuitable for inclusion in the study.

This multicenter, prospective cohort study aims to enroll approximately 3,500 adult women in China who are at medium-to-high risk for endometrial cancer according to Chinese clinical consensus guidelines. The study population specifically includes two groups: 1) women who are scheduled for a diagnostic hysteroscopy due to these risk factors, and 2) women who are currently undergoing conservative treatment (such as progesterone therapy or endometrial ablation) for existing endometrial lesions and have not received chemotherapy. All participants must have an intact cervix and be willing to participate in follow-up assessments. Participants will be followed for up to 12 months, with the enrollment target set to observe at least 20 endpoint events (diagnosis of endometrial intraepithelial neoplasia or invasive cancer).