Effect of immunonutrition on surgery outcomes in cancer patients: evidence from an umbrella review on interventional and observational meta-analyses

Malnutrition is highly prevalent in cancer patients, leading to increased post-surgical complications. This umbrella review of meta-analyses aims to investigate the effect of immunonutrition on surgery outcomes in Cancer patients. MEDLINE/PubMed, SCOPUS, and WOS databases were investigated from their inception until Sep 2025. Meta-analysis investigating the impact of immunonutrition (or its components) on overall complications, infectious complications, non-infectious complications, mortality, surgical-site infections, anastomotic leak, and length of hospital stay in patients with cancer. Pooled effect sizes and CIs were calculated using a random-effects model. Fifty-four studies were included in the umbrella review. The pooled results showed RR = 0.79; 95%CI: 0.70–0.88; I2 = 39.5% for postoperative overall complications, RR = 0.61; 95%CI: 0.58–0.65; I2 = 47.3% for infectious complications, RR = 0.88; 95%CI: 0.82–0.94; I2 = 0% for non-infectious complications, HR = 0.86; 95%CI: 0.74–0.99; I2 = 0% for mortality, RR = 0.66; 95%CI: 0.59–0.74; I2 = 6.5% for surgical-site infection, RR = 0.69; 95%CI: 0.62–0.77; I2 = 0% for anastomotic leak, and WMD=-1.75 days; 95%CI: -2.09,-1.41; I2 = 90.3% for length of hospital stay in immunonutrition intervention compared to control groups. Subgroup analysis by time of intervention showed that postoperative intervention is more effective in reducing overall complications (RR = 0.69; 95%CI:0.54–0.89) and the length of hospital stay (2.26 days, P = 0.001) compared to preoperative or perioperative intervention. Cancer patients undergoing surgery may benefit from immunonutrition. Postoperative intervention is more effective than pre-or perioperative intervention.