Mr Thomas is a 62 year old retired solicitor who presents with a 6 month history of weight loss and diarrhoea. He estimates he has lost roughly 6kg over this time despite his usual oral intake, but is uncertain having not weighed himself much in the past. There is no rectal bleeding, abdominal pain or family history of malignancy. Past medical history includes haemorrhoids and Hypertension. Abdominal examination and rectal examination are normal and observations are stable.
What is the next most appropriate course of action?