All adult patients with colorectal cancer presenting within the Sahlgrenska University Hospital or treated at any time at Sahlgrenska University Hospital are eligible and will be asked to participate. We already have biopsies taken at surgery in patients that receive surgery, but this study will include all patients and the biopsies will be taken during endoscopy for diagnosis of the primary tumour. Biopsies will then be taken during follow-up exams prior surgery but after neoadjuvant treatment. Biopsies will also be taken during surgery and in cases where surgery is not necessary biopsies will be taken regularly during follow-up exams. Blood samples and in relevant cases urinary samples and mouth swabs will be taken at all timepoints when biopsies are taken. If it is not possible to take biopsies prior treatment blood samples will still be drawn.