Impact of enteral immunonutrition on infectious complications and immune and inflammatory markers in cancer patients undergoing chemotherapy: a systematic review of randomised controlled trials

Background: there is increasing awareness of the importance of nutritional support in cancer treatment including the interaction with immunity. Immunonutrition is the provision of one or more nutrients (e.g. Vitamins A, D, or E, omega-3 fatty acids, arginine and glutamine) known to modulate immune function when given at levels above those normally encountered in the diet in order to support immune system function or modulate its activity, including control of inflammation. We reviewed the role of oral or enteral immunonutrition versus standard nutrition on infection and infection-related biomarkers in adult cancer patients undergoing chemotherapy.Methods: a systematic search of oral or enteral immunonutrition versus standard nutrition in adult cancer patients during chemotherapy with or without radiotherapy or haematopoietic stem cell transplant was conducted in MEDLINE, EMBASE and CENTRAL. The search was limited to randomised controlled trials. Our primary outcome was infectious episodes or immune-related biomarkers (e.g. immune cell numbers, inflammatory markers). Secondary outcomes included incidence of malnutrition or cachexia, non-infection related adverse events (AEs), rate of remission, survival, and delays or incomplete cycles of chemotherapy. Risk of bias was assessed using ROB 2.0 and study quality was assessed using CASP for RCTs.Results: the search yielded seven studies involving 521 patients (261 immunonutrition, 260 control) for analysis. All studies enrolled patients with solid tumours (no haematological malignancies). Studies were heterogenous for cancer type (upper gastrointestinal, head and neck, pancreatic and lung), immunonutrient composition (omega-3 fatty acids, vitamin A, E, glutamine, arginine or nucleotides), delivery route (enteral nutrition or oral nutritional supplement) and control used. Intervention period ranged from 4 to 14 weeks. No study reported absolute number of infections. Three studies reported AEs including potential infectious episodes of febrile neutropenia, pneumonitis and mucositis with oral candidiasis. Some studies report a decrease in blood concentrations of CRP and TNF-α with immunonutrition.Conclusion: there is currently insufficient evidence to define a role for immunonutrition on infectious episodes during chemotherapy in adult cancer patients. Further well-defined studies that account for degree of malnutrition, dose, timing and duration of immunonutrition in specific well-defined cancer groups using a standardised outcome framework are needed.