RecruitingProcedureColorectal Omics and OfCS ProteoglycansThis observational study aims to test proteomics, metabolomics and proteoglycans as predictors of postoperative complications after colorectal surgery and as biomarkers of colorectal cancer. The main questions to answer are: * can these biomarkers predict anastomotic leakages * can these biomarkers predict recurrence after colorectal cancer * can these biomarkers be used as diagnostic tests for colorectal cancer * can these biomarkers be identified in the tumor Participants will undergo elective colorectal resection or stoma closure.