Aims:
To map the clinical trial evidence underpinning two widely used adjunctive cancer interventions, nutritional supplements and medicinal mushrooms, across three linked syntheses.
Methods:
An umbrella review searched five databases (2019–2024) for systematic reviews of nutritional supplements for treatment-related side effects, appraised using AMSTAR-2 and GRADE. Mushrooms, excluded there as herbal medicines, were addressed by two scoping reviews (JBI, PRISMA-ScR) searching English, Chinese, Japanese and Korean databases without language restriction for clinical studies in breast and lung cancer. Screening and appraisal were independent and in duplicate.
Results:
This syntheses covers 52 reviews reporting 250 randomised trials, and 197 primary mushroom studies.
The umbrella review found moderate-certainty evidence only for amino acids and oral proteolytic enzymes for radiation dermatitis, and N-acetylcysteine for peripheral neuropathy; all other findings were low or very low certainty, and 50 of 51 reviews were of low or critically low quality.
The breast cancer review identified 47 studies (31 randomised), 36 conducted in China; eleven mushroom species were studied, most often Lentinula edodes (18), Poria cocos (7) and Trametes robiniophila (7), predominantly during chemotherapy (30) or after surgery (10), with immune (21) and inflammatory (12) biomarkers the commonest outcomes.
The lung cancer review identified 150 studies (134 randomised; 9,934 participants), all conducted in China or Japan; Lentinus edodes as lentinan injection accounted for 103 trials. Toxicity (89 studies), quality of life (76), tumour size (75) and survival (17) were reported.
Conclusions
Across all three syntheses reported effects were consistently favourable but certainty uniformly low: supplement reviews were methodologically weak, and mushroom trials geographically concentrated, open-label and poorly reported. Clinicians can convey the direction of evidence and but need also to note the level of uncertainty. Rigorous trials using standardised preparations and validated outcomes are the priority.