Oral nutrition interventions in patients undergoing gastrointestinal surgery for cancer: A systematic literature review.

Weight loss and poor food intake have been shown to affect several outcomes in patients undergoing surgery for gastrointestinal cancer. This review aims to examine the effect of pre-, post- or perioperative nutrition interventions focused on increasing oral energy or protein intake in patients undergoing surgery for gastrointestinal cancer. Interventions using standard oral nutrition supplements and/or dietary counselling were included. The primary outcome was weight change, and secondary outcomes were energy and protein intake. A secondary aim was to examine this effect in malnourished patients. Embase, Medline, CINAHL and CENTRAL were searched from inception to September 2019 for relevant randomised controlled trials. Study quality was assessed using the revised Cochrane Collaboration risk of bias tool for randomised trials. The quality of evidence for each outcome was assessed using GRADE. Fourteen articles met the inclusion criteria. Studies assessed patients undergoing surgery for gastric, colorectal, oesophageal and pancreatic cancers. The interventions studied included oral nutrition supplements and/or dietary counselling. Five studies reported preoperative interventions; five studies reported post-operative interventions; six studies reported post-discharge interventions; and two studies reported perioperative interventions. Overall, low or very low quality evidence was found to support the use of oral nutrition supplements to positively influence weight and increase energy and protein intake in the preoperative period and immediate post-operative period. Very low quality evidence was found to support the use of oral nutrition interventions to influence weight, energy or protein intake in the post-discharge period. Very limited evidence with high risk of bias was found to support positive effects of nutrition intervention in malnourished patients. This review demonstrates limited evidence for the use of oral nutrition supplements to increase intake and positively influence weight in patients undergoing surgery for gastrointestinal cancer. Overall, results were heterogeneous leading to inconsistent results. Further research into optimal nutrition support interventions and timing of interventions is required.