Oral Nutrition as a Form of Pre-Operative Enhancement in Patients Undergoing Surgery for Colorectal Cancer: A Systematic Review.

Background: Nutritional status has major impacts on the outcome of surgery, in particular in patients with cancer. The aim of this review was to assess the merit of oral pre-operative nutritional support as a part of prehabilitation in patients undergoing surgery for colorectal cancer. Methods: A systematic literature search and meta-analysis was performed according to the Preferred Reporting of Systematic Reviews and Meta-Analyses (PRISMA) recommendations in order to review all trials investigating the effect of oral pre-operative nutritional support in patients undergoing colorectal surgery. The primary outcome was overall complication rate. Secondary outcomes were incision infection rate, anastomotic leakage rate, and length of hospital stay. Results: Five randomized controlled trials and one controlled trial were included. The studies contained a total of 583 patients with an average age of 63y (range 23-88y), of whom 87% had colorectal cancer. Malnourishment rates ranged from 8%-68%. All investigators provided an oral protein supplement. Overall patient compliance rates ranged from 72%-100%. There was no significant reduction in the overall complication rate in the interventional groups (odds ratio 0.82; 95% confidence interval 0.52-1.25). Conclusion: Current studies are too heterogeneous to conclude that pre-operative oral nutritional support could enhance the condition of patients undergoing colorectal surgery. Patients at risk have a relatively lean body mass deficit (sarcopenia) rather than an absolute malnourished status. Compliance is an important element of prehabilitation. Targeting patients at risk, combining protein supplements with strength training, and defining standardized patient-related outcomes will be essential to obtain satisfactory results.