Gut-Brain Axis and Dietary Patterns in Adolescent and Young Adult Childhood Cancer Survivors: A Systematized Narrative Review
This systematized narrative review maps hypothetical pathophysiological mechanisms between treatment-induced dysbiosis and delayed neurocognitive sequelae in adolescent and young adult cancer survivors, without establishing causality or demonstrating efficacy of dietary interventions in this population.
| Population | Adolescents (10–19 years) and young adults (up to 25 years) who survived childhood cancer, including leukemias, solid tumors, and HSCT recipients |
|---|---|
| Intervention | Exposure to intensive oncological treatment (chemotherapy, cranial radiotherapy, HSCT) and post-treatment dietary patterns (e.g., MIND diet, probiotics, psychobiotics) |
| Comparator | No uniform comparator; narrative review without standardized control group |
| Outcome | Gut microbiome alpha diversity post-chemotherapy; Neurocognitive performance (executive function, attention); Systemic inflammatory markers (pro-inflammatory cytokines); BDNF levels; Psychosocial outcomes (depression, anxiety); Quality of life (QoL); Efficacy of dietary interventions (MIND diet, probiotics) on neurocognitive outcomes |
Summary of findings
| Outcome | Effect | 95% CI | Certainty | Clinical relevance | Notes |
|---|---|---|---|---|---|
| Gut microbiome alpha diversity post-chemotherapy | narrative synthesis only; in the pooled statistic reported | — | Very low | — | |
| Neurocognitive performance (executive function, attention) | narrative synthesis only; in the pooled statistic reported | — | Very low | — | |
| Systemic inflammatory markers (pro-inflammatory cytokines) | narrative synthesis only; in the pooled statistic reported | — | Very low | — | |
| BDNF levels | narrative synthesis only; in the pooled statistic reported | — | Very low | — | |
| Psychosocial outcomes (depression, anxiety) | narrative synthesis only; in the pooled statistic reported | — | Very low | — | |
| Quality of life (QoL) | narrative synthesis only; in the pooled statistic reported | — | Very low | — | |
| Efficacy of dietary interventions (MIND diet, probiotics) on neurocognitive outcomes | no RCT identified in this population; in the statistic available | — | Very low | — |
Context
Over 85% of children with cancer survive in high-income countries, generating a growing cohort with late neurocognitive and psychosocial sequelae. The pathogenesis of these sequelae has historically been attributed to direct neurotoxicity, but emerging evidence implicates the gut-brain axis. The absence of robust longitudinal and interventional studies in this specific population limits clinical translation.
What the study showed
The study generates no primary data; it synthesizes translational evidence from animal models, observational studies, and reviews. Murine models show that post-chemotherapy dysbiosis reduces alpha diversity and depletes Lactobacillus and Bifidobacterium, with increased pro-inflammatory cytokines and reduced BDNF. Observational clinical studies in ALL survivors show an association between persistent dysbiosis and worse neurocognitive performance, but no uniformly reported effect size with 95% CI. No RCT of dietary intervention in AYA survivors was identified as a primary outcome of this review.
How it was done
Systematized narrative review (SANRA/PRISMA), with searches in PubMed/MEDLINE, Embase, Cochrane Library, Scopus, and Web of Science, covering 2010–2026, in English and Polish. Two independent reviewers performed screening; discrepancies resolved by consensus or third arbitrator. Narrative synthesis was adopted due to methodological heterogeneity precluding formal meta-analysis.
Effect magnitude
No pooled effect size with 95% CI was calculated; the review does not report consolidated RR, OR, SMD, or MD for any outcome. Effect magnitude remains undetermined in this publication.
Risk of bias
Systematized narrative review without formal meta-analysis; extreme heterogeneity between preclinical (murine) and observational clinical studies prevents consolidated effect estimation. Risk of bias of included studies was not assessed using standardized tools (RoB 2, ROBINS-I, or AMSTAR-2 not explicitly applied). Inclusion of gray literature and preprints for 'broader context' introduces publication and selection bias risk.
What this study does NOT prove
This study does NOT demonstrate causality between intestinal dysbiosis and neurocognitive sequelae in human childhood cancer survivors. It does NOT validate any dietary or probiotic intervention for prevention or treatment of neurocognitive deficits in this population.
In clinical practice
There is insufficient evidence to recommend specific dietary interventions (MIND diet, probiotics) as neuroprotective strategies in AYA survivors of childhood cancer based on this review. Screening for late neurocognitive sequelae remains indicated by existing survivorship guidelines. Assessment of nutritional status and gut health may be integrated into multidisciplinary follow-up, but without a validated protocol derived from this study.
Limitations
Systematized narrative review without formal meta-analysis; extreme heterogeneity between preclinical (murine) and observational clinical studies prevents consolidated effect estimation. Risk of bias of included studies was not assessed using standardized tools (RoB 2, ROBINS-I, or AMSTAR-2 not explicitly applied). Inclusion of gray literature and preprints for 'broader context' introduces publication and selection bias risk.
What is still missing
Longitudinal RCTs evaluating dietary interventions (MIND diet, probiotics, psychobiotics) on validated neurocognitive outcomes in AYA survivors of childhood cancer are needed. Prospective cohort studies with longitudinal microbiome profiling and serial neurocognitive assessment in this population are absent.
Technical appendix
Version history
- 1.0 · 2026-09-23 — Auto-generated under Evidence Standard v1.0