Impact of enteral nutrition timing on clinical outcomes after gastrointestinal cancer surgery or in critically ill patients

BACKGROUNDNutritional status is a key factor in determining clinical outcomes and directly affects tolerance to surgical treatment, postoperative recovery, and long-term prognosis.The optimal timing for initiating enteral nutrition (EN) remains unclear as patients in critical conditions and after gastrointestinal tumor surgery often experience gastrointestinal dysfunction and intolerance to nutritional support.The conclusions of relevant domestic and international studies have not yet reached a unified consensus, and more systematic research is required to verify and provide evidence-based medical evidence for clinical decision-making. AIMTo explore the impact of EN timing on clinical outcomes after surgery for gastrointestinal tumors or those in critical condition. METHODSSystematic literature searches of electronic databases were conducted from inception to May 2026 to identify relevant studies investigating the impact of EN initiation timing on clinical outcomes in patients after gastrointestinal tumor surgery or in critical conditions.Methodological quality was assessed using the Cochrane Risk of Bias tool (RoB 2) for randomized controlled trials and the Newcastle-Ottawa Scale for retrospective cohort studies.Pooled effect estimates were calculated using random-or fixed-effects models depending on heterogeneity.Subgroup analyses were performed by patient type (gastrointestinal cancer surgery vs critical illness) for infection and overall complications, and by follow-up duration for mortality. RESULTS / 38Ten studies met the inclusion criteria.Compared with delayed EN, early EN significantly shortened hospitalization time [mean difference = -3.69;95% confidence interval (95%CI): -6.20 to -1.18; P = 0.004] and reduced the incidence of mechanical ventilation (odds ratio = 0.52; 95%CI: 0.32-0.85;P = 0.009).There were no significant differences in the 28-day mortality, infection rate, or total complication rate (P > 0.05).Subgroup analysis according to follow-up duration revealed no statistically significant differences in outcome indicators, suggesting that follow-up duration did not significantly affect the mortality estimate.Subgroup analyses by patient type showed no significant between-subgroup differences for infection (P = 0.31) or overall complications (P = 0.24).Notably, the hospital-stay benefit in gastrointestinal cancer patients was derived from a single study and should be interpreted with caution. CONCLUSIONEarly EN is associated with shorter hospital stay and reduced mechanical ventilation without increasing mortality, infection, or overall complications in a mixed population of postoperative gastrointestinal cancer and critically ill patients.However, the evidence specific to gastrointestinal cancer surgery remains extremely limited, as this subgroup is represented by only two studies, and the majority of the data are derived from critically ill populations.Therefore, our findings are primarily applicable to mixed critically ill patients and should be extrapolated to gastrointestinal cancer surgery populations with caution.High-quality, population-specific studies are needed to confirm these findings.