The Efficacy of Watch and Wait Strategy or Surgery After Neoadjuvant Immunotherapy for Locally Advanced Colorectal Cancer With dMMR/MSI-H Guided by MRD Dynamic Monitoring: A Single-center, Open-label, Prospective, Phase II Clinical Trial.

This study looks at whether some patients with locally advanced colorectal cancer who achieve a complete response (no detectable cancer) after immunotherapy can safely skip surgery — a "watch and wait" approach — guided by blood tests that detect tiny amounts of cancer DNA. This applies only to tumors with a specific DNA repair defect (called dMMR or MSI-H). **You may be eligible if...** - You have been confirmed to have colorectal cancer (specifically adenocarcinoma) - Your tumor has the dMMR or MSI-H marker (a specific molecular feature detectable by biopsy) - Your cancer is locally advanced (stage II–III) with no distant spread - You have no signs of bowel obstruction (or it has been resolved) **You may NOT be eligible if...** - Your tumor does not have the dMMR/MSI-H marker - Your cancer has spread to other organs or distant lymph nodes - You have had prior treatment for colorectal cancer Talk to your doctor to see if this trial is right for you.