ctDNA Testing to Inform Standard-of-Care Treatment Decisions in People With Endometrial Cancer

This study is testing whether a blood test that detects tumor DNA (called ctDNA) can help guide treatment decisions for people with advanced or recurrent endometrial (uterine) cancer. Researchers want to know if tracking tumor DNA in the blood can show whether treatment is working. **You may be eligible if...** - You have been diagnosed with endometrial cancer confirmed by biopsy - Your cancer is advanced (stage III with remaining disease, or stage IV) or has come back after treatment - Your tumor has been tested and found to have a mismatch repair deficiency (MMR-D) or microsatellite instability (MSI-H) — a feature that makes certain immunotherapy drugs more effective - You are eligible for standard chemotherapy plus an immune checkpoint inhibitor **You may NOT be eligible if...** - Your cancer is early stage and fully removed without remaining disease - Your tumor does not have the MMR-D or MSI-H marker - You have untreated brain metastases - You are not able to receive the standard treatment combination Talk to your doctor to see if this trial is right for you.