Background
Among adults with cancer, malnutrition is associated with decreased treatment completion, more treatment harms and use of healthcare, and worse short-term survival. To inform the National Institutes of Health Pathways to Prevention (P2P) workshop, Nutrition as Prevention for Improved Cancer Health Outcomes, this systematic review examined the evidence for the effectiveness of providing nutritional interventions before or during cancer therapy to improve outcomes of cancer treatment.
Methods
We identified randomized controlled trials (RCT) enrolling ≥50 participants published from 2000 through July 2022. We provide a detailed evidence map for included studies and grouped studies by broad intervention and cancer types. We conducted risk of bias and qualitative descriptions of outcomes for intervention and cancer types with a larger volume of literature.
Results
From 9,798 unique references, 206 RCT from 219 publications met inclusion criteria. Studies primarily focused on non-vitamin/mineral dietary supplements, nutrition support, and route or timing of inpatient nutrition interventions for gastrointestinal or head and neck cancers. Most studies evaluated changes in body weight/composition, adverse events from cancer treatment, length of hospital stay, or quality of life. Few studies were conducted within the U.S. Among intervention and cancer types with a high volume of literature (n = 114), 49% (n = 56) were assessed as high risk of bias. Higher quality studies (low- or medium risk-of-bias) reported mixed results on the effect of nutritional interventions across cancer and treatment-related outcomes.
Conclusions
Methodological limitations of nutritional intervention studies surrounding cancer treatment impair translation of findings into clinical practice or guidelines.