Given the absence of good-quality and evidence-based data, it has been agreed that a trial considering adjuvant chemotherapy versus no chemotherapy was appropriate for patients with stage I-III SBA in whom the oncologist and patient feel that the benefit of adjuvant chemotherapy is uncertain. For those patients with stage I-III SBA who, with their oncologists, feel that the potential benefit of adjuvant chemotherapy is certain (and hence are not willing to accept randomisation to the 'no chemotherapy' arm), a randomisation between single agent fluoropyrimidine versus doublet fluoropyrimidine and oxaliplatin chemotherapy will be offered. Tumour stage will be used as a stratification factor. Those patients who do not consent to be randomised will be offered registration to allow collection of demographic, clinicopathological and survival data, thereby making optimal use of the rare patient population available. In addition, archival Formalin Fixed Paraffin Embedded (FFPE) tissue and contemporaneous venous blood samples will be collected from every registered patient to allow molecular profiling and future translational research. A questionnaire about underlying risk factors (e.g. Crohn's disease, coeliac disease, Lynch syndrome etc) will be completed along with the other collected data on all registered patients.