DANISH.MRD: Danish Assessment of Minimal Residual Disease by Liquid Biopsies

DANISH.MRD part I - Surgery Inclusion Criteria: * Colon or rectal cancer, clinical tumor stage I-III. * Patient able to understand and sign written informed consent. * Scheduled for curative-intent resectional surgery (including "compromised" curative resections). Exclusion Criteria: * Hereditary colorectal cancer linked to familial colonic polyposis or Lynch syndrome. * Inflammatory bowel disease (Crohn's disease or ulcerative colitis). * Verified distant metastases. * Malignant colorectal polyps diagnosed after polypectomy. * Patients who are unlikely to comply with the protocol (e.g., uncooperative attitude, inability to return for subsequent visits) and/or otherwise considered by the Investigator to be unlikely to complete the study. DANISH.MRD part II - Surveillance Inclusion Criteria: * Participation in DANISH.MRD part I - Surgery. * Colorectal cancer, UICC stage III. * Has received curative-intent resection and is a candidate for adjuvant chemotherapy (3- or 6-months regime). Exclusion Criteria: * Not treated with adjuvant chemotherapy * Treated with neoadjuvant chemo-radiation therapy. * Synchronous colorectal and non-colorectal cancer diagnosed per operative (except skin cancer other than melanoma). * Other cancers (excluding colorectal cancer or skin cancer other than melanoma) within 3 years from eligibility screening. * Patients who are unlikely to comply with the protocol (e.g., uncooperative attitude, inability to return for subsequent visits) and/or otherwise considered by the Investigator to be unlikely to complete the study.