Perioperative immunonutrition in gastrointestinal malignancies: Clinical benefit, patient selection, and current uncertainties.

Patients undergoing surgery for gastrointestinal malignancies may present with malnutrition, systemic inflammation, immune dysfunction, and impaired intestinal barrier function, all of which can increase susceptibility to postoperative infection and delayed recovery. Perioperative immunonutrition involves the administration of nutritional formulations enriched with immunomodulatory substrates, most commonly arginine, omega-3 fatty acids, L-glutamine, and nucleotides, as an adjunct to standard nutritional support. This narrative review examines the biological rationale, clinical evidence, patient-selection considerations, and current uncertainties surrounding immunonutrition in gastrointestinal cancer surgery. The most consistent evidence supports a reduction in postoperative infectious complications, with the clearest benefit signals reported in nutritionally vulnerable patients and those undergoing major upper gastrointestinal surgery. Effects on length of hospital stay, wound healing, and short-term recovery are less consistent and appear to vary according to tumor site, baseline nutritional risk, operative stress, formulation, timing, and integration with enhanced recovery pathways. Evidence for mortality, recurrence, and long-term survival remains limited and inconsistent. Perioperative immunonutrition should therefore be considered a selective, risk-stratified adjunct to standard nutritional care rather than a universal intervention. Future studies should use standardized protocols, clearly defined patient populations, and clinically meaningful endpoints to clarify its role in contemporary gastrointestinal surgical oncology.