This project is the first application, which is applied as a single center project and applied according to the screening quantity. This project is a multi-omics approach to explore biomarkers associated with prognosis after secondary radical resection of recurrent and metastatic colorectal cancer. Main research objectives: 1. To detect DNA mutation and methylation in tumor tissues by NGS detection technology (the methylation dimension should be detected in adjacent tissues at the same time), and to explore specific molecular markers related to prognosis; 2. Using NGS test technology of blood in patients with preoperative and postoperative blood ctDNA mutations and methylation double dimension testing, respectively, to explore the preoperative and postoperative ctDNA mutations and the correlation between methylation status and recurrence, including but not limited to predict patients with recurrence of sensitivity, specificity, positive predictive value, negative predictive value and recurrence warning time and other indicators. Main contents: This study intends to include single site for the first time/organ metastasis after radical treatment and surgical indications again in patients with colorectal adenocarcinoma (including but not limited to spread to the liver, lung metastasis, peritoneal metastasis, lymph node metastasis and other organ metastasis), collected in patients with preoperative peripheral blood and tissue samples, tissue adjacent to carcinoma and postoperative peripheral blood, NGS detection technology was used to detect DNA and mutation in the relevant samples, combined with clinical treatment and prognosis information of patients, and then explore biomarkers for predicting recurrence risk.