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Nutrition as Prevention for Improved Cancer Health Outcomes

Draft Comments Jul 26, 2022
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Main Points

  • Two decades of randomized trial evidence over 180 studies on nutrition interventions for adults prior to and/or during cancer treatment focused on use of dietary supplements, nutrition support (including oral nutrition supplements), and the route or timing of nutrition interventions within gastrointestinal and head and neck cancers.
  • Studies focused on evaluating changes in weight/body composition, adverse events, length of hospital stay, and quality of life.
  • Among studies with a high volume of literature, which predominately examined dietary supplements and nutrition support in gastrointestinal and head and neck cancers, 10 percent (n=10) were rated as low risk of bias (higher quality), 39 percent (n=39) medium risk of bias and 51 percent (n=51) as high risk of bias (lower quality).
  • Low- and medium-risk-of-bias studies reported mixed results on the effect of nutrition interventions across outcomes for cancer and cancer treatment (detailed in the evidence summary results below).
  • Few (5%, N=8) studies reported a formal cost-effectiveness analysis or provided costs detailed by intervention component; generally, these studies reported only overall costs from inpatient non-U.S. settings.
  • Future research would benefit from a detailed assessment of a subset of studies in this evidence map; that subset would include studies focused on priorities and interventions most relevant to specific stakeholders (e.g., oncologists, patients, dietitians, researchers, policymakers). Future studies could then be specifically designed to evaluate the main outcomes of interest relevant for clinical practice.
  • Future research would also benefit from a creation of standardized taxonomies for interventions and outcomes as well as more rigorous design and reporting of nutrition interventions.

Structured Abstract

Objective. To understand the evidence base for nutrition interventions delivered prior to or during cancer treatment for preventing and treating negative cancer and cancer treatment-related outcomes among individuals with or at risk for malnutrition. The primary purpose was to inform the NIH Pathways to Prevention workshop, Nutrition as Prevention for Improved Cancer Health Outcomes, held July 26 – 28, 2022.

Data Sources. We searched Ovid Medline®, Ovid Embase®, and Cochrane Central Register of Controlled Trials to identify studies from 2000 through May, 2021. We will update results during the public comment period. We conducted grey literature searches to identify additional resources relevant to cost-effectiveness.

Review Methods. We searched for studies that evaluated a broad range of nutrition interventions (e.g., dietary supplements, nutrition support, nutrition counseling) for preventing and treating negative outcomes of cancer and cancer-related treatment. Eligible studies included randomized controlled trials (RCT) with enrollment ≥50 participants. We extracted basic study information from all eligible studies, then grouped studies by broad intervention and cancer types. We provide a detailed evidence map for all included studies, but conducted risk of bias and additional qualitative descriptions of outcomes for only those intervention and cancer types with a larger volume of literature.

Results. We identified 9,181 unique references, with 184 studies from 194 publications reporting RCTs of nutrition interventions to potentially improve negative outcomes of cancer and cancer –related treatment. Two decades of randomized trial evidence on nutrition interventions for adults prior to and/or during cancer treatment primarily focused on dietary supplements, nutrition support (including oral nutrition supplements), and the route or timing of nutrition interventions within gastrointestinal and head and neck cancers in the inpatient setting. Most studies evaluated changes in weight/body composition, adverse events, length of hospital stay and quality of life. Among intervention and cancer types with a high volume of literature (n=100), which predominately included studies in dietary supplements and nutrition support in gastrointestinal and head and neck cancers, 10 percent (n=10) were rated as low risk of bias (higher quality), 39 percent (n=39) medium risk of bias, and 51 percent (n=51) high risk of bias (lower quality). Low- and medium-risk-of-bias studies reported mixed results on the effect of nutrition interventions across cancer and treatment-related outcomes. Although the evidence map shows a large volume of studies evaluating nutrition interventions and outcomes, studies showed high heterogeneity across study populations, interventions, and outcomes (measure definitions, timing of measurements), even within nutrition intervention categories, therefore we could not aggregate results.

Among studies evaluating effectiveness of nutrition interventions, the few (5 percent, N=8) that published cost information related to the intervention were predominantly conducted in inpatient settings in non-U.S. health systems. Of the 8 studies that published cost information, few conducted formal cost-effectiveness analyses, but those that did demonstrated cost-savings from inpatient nutrition interventions in non-U.S. health systems (e.g., Italy).

Conclusions. Although overall RCT evidence focused on a wide range of nutrition interventions, studies were concentrated in use of dietary supplements, nutrition support, and the route or timing of nutrition interventions within gastrointestinal and head and neck cancers in inpatient settings. Among interventions with the highest volume of literature, the majority of studies were rated as of high risk of bias. Our findings point to the need for rigorous new research to bolster the evidence base. Specifically, the field needs a more detailed future evaluation of a subset of nutrition interventions contained in this evidence map that focus on priorities most relevant to specific stakeholders (e.g., oncologists, patients, dietitians, researchers, policymakers). Further, studies should be specifically designed to evaluate the main outcomes of interest for clinical practice. Future research would also benefit from creation of standardized taxonomies for interventions and outcomes as well as more rigorous design and reporting of nutrition interventions. As mentioned, heterogeneity of populations, interventions, comparators and outcomes precluded aggregation. Currently, the quality and heterogeneity of the studies limit the ability to translate findings into clinical practice or guidelines. In order to inform development of these guidelines, coordinated efforts are required to develop detailed conceptual frameworks for mechanisms of nutrition interventions most relevant to clinical care providers and patients. Such frameworks would help inform priorities for future research as well as guide practice and policy.

Project Timeline

Nutrition as Prevention for Improved Cancer Outcomes

Oct 4, 2021
Topic Initiated
Oct 8, 2021
Jul 26, 2022
Draft Comments
Jul 26, 2022 - Aug 23, 2022
Page last reviewed July 2022
Page originally created July 2022

Internet Citation: Draft Comments: Nutrition as Prevention for Improved Cancer Health Outcomes. Content last reviewed July 2022. Effective Health Care Program, Agency for Healthcare Research and Quality, Rockville, MD.
https://effectivehealthcare.ahrq.gov/products/improved-cancer-outcomes/draft-comment

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