The purpose of the study is to see if this imaging method can effectively map the sentinel lymph nodes, which are the first few lymph nodes where cancer is likely to spread. During the study, participants will undergo a PET/CT scan with Gallium-68-tilmanocept to detect these lymph nodes. The study will also compare the results of this scan with another method that uses a different substance called ICG and a special light to see the lymph nodes during surgery.

Throughout the study, researchers will also look at the condition of the lymph nodes to see if they contain cancer cells. They will check for any side effects that might occur from the imaging process. The study aims to provide more information on how well this new imaging technique works for patients with endometrial cancer.

Participants in the study will receive Giredestrant and undergo regular assessments to monitor how the cancer responds to the treatment. The main goal is to evaluate the reduction in cancer at a 6-month check, alongside the safety of the drug. More detailed assessments will include checking the extent of cancer regression and monitoring its duration, as well as collecting blood samples to measure the amount of Giredestrant in the body at specified times.

This trial does not use a comparison group receiving a placebo, meaning all participants will be administered the active treatment. Patients will provide samples before and during the study for more comprehensive examination, including scans such as MRI or CT to monitor the presence and spread of the cancer. The information gained from this study may help in understanding how effective Giredestrant is as a therapy for this specific cancer type.