Nutritional interventions in randomised clinical trials for people with incurable solid cancer: A systematic review

Malnutrition is highly prevalent in those with cancer and more so in those with incurable cancer. In incurable cancer, it is widely agreed that optimal nutritional care has the potential to positively impact patient and caregiver distress and oncological outcomes. The aim of this systematic review was to describe the diversity and frequency of nutritional interventions, whether given in isolation or as part of a multimodal intervention in those with incurable cancer, in randomised controlled trials. The secondary aims were to describe adherence and their efficacy.

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. The following databases were searched electronically: Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica database (EMBASE), Cumulated Index to Nursing and Allied Health Literature (CINAHL) and Cochrane Central Register of Controlled Trials (CENTRAL) with the time frame from January 2000 to 7th September 2023. Eligible studies included adult patients (≥18 years) diagnosed with incurable solid cancer with a sample size ≥40. Studies were to be primary research and delivered for at least 14 days to allow for efficacy. They were to include a nutritional intervention encompassing at least one of the following: dietary counselling, oral nutritional supplements (ONS), enteral tube feeding and/or parenteral nutrition (PN), given in isolation or as part of a multi-modal intervention. Studies were excluded if the population contained patients who had completed curative treatment or are being treated with curative intent, haematological cancers, or if they examined the effects of micronutrients, proteins, amino acids or fatty acids given in isolation. The quality of the included studies was assessed using the Cochrane risk of bias tool for randomised trials (RoB2). A balloon plot was produced to present the results in addition to a table with a narrative summary of the primary outcomes.

A total of 7968 studies were identified, of which 18 met the eligibility criteria. This included 2720 study participants. The included studies comprised: multimodal interventions (n = 7), dietary counselling (n = 2), nutritional supplementation with or without dietary counselling (n = 7) and PN (n = 2). Primary outcomes included quality of life (QoL), body composition and nutritional status. For QoL, this was reported in 15 studies, 4 studies showed a significant improvement. Body composition was evaluated in 15 studies, 5 of which showed a significant improvement in body weight and two in fat-free mass (FFM). Nutritional status was reported in 6 studies with one showing a significant difference in Patient-Generated Subjective Global Assessment (PG-SGA) score. The risk of bias was deemed 'low' in 6 studies, with 'some concerns' in 10 studies and a 'high risk' in 2 studies. There was heterogeneity between the studies.

This systematic review has highlighted some positive findings in regard to QoL, body weight and nutritional intake. Optimum nutritional intervention was not identified. Future studies should evaluate the effectiveness of earlier nutritional interventions at the point of diagnosis, including regular reviews and the impact this has on nutritional outcomes, QoL and overall survival (OS).