Study Design
The OCEaN trial is a multicentre randomised controlled trial. The control group will continue to eat their usual unrestricted diet before surgery and the intervention group will receive a 6-week course of EEN before surgery. Participants from both groups will collect stool samples at baseline (study entry point for the control group and the week before starting EEN for the intervention group), before surgery, 6 weeks after surgery and 6 months after surgery.