Circulating Tumour DNA (ctDNA) in Patients With Colorectal Cancer and the Relationship to Imaging Features of Extramural Venous Invasion

This study does not involve randomization or treatment. Eligible patients have colorectal adenocarcinoma with no metastases eligible for curative surgery. A pre operative staging scan must have been completed within 6 weeks prior to surgery. Two x 20ml blood samples will be taken from each patient, one prior to and one during or within 24hrs after surgery. Patients are annually followed up to 3 years.