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

The researchers are doing this study to evaluate the use of circulating tumor DNA (ctDNA) testing in making treatment decisions for advanced/recurrent endometrial cancer that has a change (mutation) in the mismatch repair deficient (MMR-D) gene or microsatellite instability high (MSI-H) gene. The researchers will see how doctors and their patients use the results of ctDNA testing after 1 year of standard chemotherapy and immune checkpoint inhibitor (ICI) treatment to decide whether to continue maintenance ICI treatment past 1 year. The researchers will also look at the health outcomes of people in this study (for example, whether they are cancer free at the end of their participation in the study).