the Role of ctDNA in Predicting the Recurrence Risk of Colorectal Cancer

Inclusion Criteria: * 1\. Patients with colorectal cancer diagnosed pathologically as stage Ⅱ and stage Ⅲ. * 2\. The patient underwent radical surgical treatment. * 3\. The patient has the results of genetic genetic testing for gastrointestinal tumors, including the genetic mutation status of MMR genes and related genes (MLH1, MSH2, MSH6, PMS2, MLH3, EPCAM). * 4\. The patient understands and is willing to sign a written informed consent document. * 5\. During the treatment process, the patient can cooperate to provide samples of each node. * 6\. The patient can provide corresponding clinical materials, including but not limited to case diagnosis, imaging evaluation, and serum protein marker test results. Exclusion Criteria: * 1\. The patient cannot provide a complete and qualified specimen. * 2\. The patient has other primary malignant tumors or serious medical illnesses. * 3\. The patient cannot cooperate with the follow-up. * 4\. Conditions that other researchers deemed inappropriate for continuing to participate in the study.