Study of Induction PD-1 Blockade (Nivolumab) in Patients With Surgically Complete Resectable Mismatch Repair Deficient Endometrial Cancer (NIVEC)

This study is testing whether giving an immunotherapy drug (nivolumab) before surgery — called neoadjuvant treatment — can improve outcomes in women with a specific type of uterine cancer that has a genetic marker called mismatch repair deficiency (dMMR), making it potentially more responsive to immunotherapy. **You may be eligible if...** - You are female and 20 years or older - You have been diagnosed with endometrial cancer or carcinosarcoma confirmed by tissue analysis - Your tumor has the dMMR (mismatch repair deficient) genetic marker - Your cancer is at stage I–IIIC2 and is resectable (can be removed by surgery) - You have signed informed consent **You may NOT be eligible if...** - Your cancer does not have the dMMR marker - Your cancer is at stage IVA or IVB - You have had prior immunotherapy or certain other treatments Talk to your doctor to see if this trial is right for you.