This study aims to review existing literature on the effect of oral nutritional supplements (ONSs) during chemotherapy in older cancer patients. Electronic databases were searched for relevant studies up to March 2024. The risk of bias in the included studies was evaluated using the Cochrane tool. Eligible studies included randomized, prospective, and retrospective studies evaluating the effect of ONSs in elderly (median age > 65 years) cancer patients during chemotherapy. Data regarding chemotherapy adherence, toxicity, overall survival, and nutritional status were extracted. A total of ten studies, involving 1123 patients, were included. A meta-analysis of the results was not conducted due to the scarcity and heterogeneity of results. Some ONSs were associated with reduced incidence of chemotherapy side-effects, particularly oral mucositis, and improved nutritional status. There was limited or no evidence regarding the impact of ONSs on chemotherapy adherence or overall survival. Various types of ONS were investigated, including multimodal intervention with tailored nutritional counseling, whey protein supplements, amino acids supplements (including immune nutrition supplements), and fish oil omega-3-enriched supplements. ONSs showed promise in reducing chemotherapy side-effects and improving nutritional status in older cancer patients, but further studies are needed to explore their efficacy on chemotherapy adherence and overall survival. Future research should consider both chronological age and frailty criteria, account for dietary habits, and use specific nutritional assessment like Bioelectrical Impedance Analysis.
Keywords: chemotherapy; nutrition therapy; nutritional status; older patients; oral nutritional supplements; systematic review.