Authoritative summary Evidence context Summary of multiple laboratory and human studies
NCI medicinal mushroom evidence summary
NCI reviews human and laboratory research on several medicinal mushrooms. The clearest human evidence discussed is for PSK, a specific Turkey Tail-derived product used with standard cancer treatment in Japan. This is not evidence that ordinary retail mushroom supplements treat cancer.
- What was studied
- Multiple mushroom products, including the specific Turkey Tail extract PSK and various Reishi preparations
- Setting
- Mixed treatment settings
- Why it ranks here
- This is an authoritative evidence map, not a single clinical experiment or a treatment endorsement.
Limits and cautions
- The summary covers different mushroom species and preparations that are not interchangeable.
- Many findings concern immune markers or laboratory models rather than survival or quality of life.
- A summary cannot replace review of the individual trial methods and risk of bias.
The FDA has not approved medicinal mushrooms as a treatment for cancer or another medical condition in the United States.
Evidence synthesis Stronger human signal 8 randomized trials, 8,009 participants
Adjuvant PSK after curative gastric cancer surgery: meta-analysis
Across eight older Japanese trials, adding PSK to postoperative chemotherapy was associated with a modest improvement in overall survival. The result applies to adjunct PSK in those treatment settings, not to Turkey Tail supplements used alone.
- What was studied
- PSK, a proprietary protein-bound polysaccharide preparation derived from cultured Turkey Tail mycelium
- Setting
- Studied with standard care
- Why it ranks here
- The signal comes from pooled randomized trials with clinical survival outcomes, but the studies are older and product-specific.
Limits and cautions
- The trials were conducted in older Japanese postoperative chemotherapy settings.
- PSK is a specific standardized preparation and should not be treated as equivalent to retail Turkey Tail powders or extracts.
- The meta-analysis does not establish PSK as a replacement for surgery or chemotherapy.
PSK is used as an adjunct in Japan. It is not FDA-approved in the United States as a cancer treatment.
Evidence synthesis Stronger human signal 3 randomized trials, 1,094 participants
Adjuvant PSK after colorectal cancer surgery: meta-analysis
A pooled analysis of three Japanese randomized trials reported better five-year overall and disease-free survival when PSK was added to postoperative chemotherapy. The finding is specific to PSK as an adjunct in the studied regimens.
- What was studied
- PSK added to postoperative fluoropyrimidine chemotherapy
- Setting
- Studied with standard care
- Why it ranks here
- The analysis pooled randomized evidence and measured clinical outcomes, while remaining limited to an older, specific treatment context.
Limits and cautions
- The chemotherapy regimens and clinical era differ from many current standards.
- The evidence concerns a standardized PSK product rather than generic Turkey Tail supplements.
- The analysis studied postoperative adjunct use, not stand-alone treatment.
PSK is not FDA-approved in the United States as a cancer treatment.
Randomized trial Promising, with limits 262 participants
PSK with chemotherapy after gastric cancer surgery: randomized trial
This older Japanese randomized trial reported better five-year disease-free and overall survival when PSK was added to postoperative chemotherapy. It does not test a retail Turkey Tail supplement or stand-alone mushroom treatment.
- What was studied
- Protein-bound PSK added to mitomycin and oral fluorouracil after curative gastrectomy
- Setting
- Studied with standard care
- Why it ranks here
- The trial measured clinical outcomes and used randomization, but it reflects one older regimen and one specific PSK product.
Limits and cautions
- The trial is from 1994 and used an older chemotherapy regimen.
- The intervention was standardized PSK, not ordinary Turkey Tail powder.
- The study evaluated adjunct use after surgery and does not support replacing standard care.
PSK is not FDA-approved in the United States as a cancer treatment.
Randomized trial Early signal 21 participants
Small randomized PSK study after stage III gastric cancer surgery
The PSK group had better reported three-year survival and a change in one immune-cell measure, but only 21 people were studied. The result is interesting and highly uncertain, so it should be treated as an early signal rather than a reliable treatment estimate.
- What was studied
- PSK 3 g/day plus tegafur-uracil after surgery, compared with tegafur-uracil alone
- Setting
- Studied with standard care
- Why it ranks here
- Randomization is a strength, but the sample is far too small for a stable estimate and the result may be exaggerated by chance.
Limits and cautions
- The sample was extremely small, with 10 participants in the PSK group and 11 in the control group.
- A large apparent effect in a very small trial may not replicate.
- The intervention and chemotherapy context do not match ordinary retail Turkey Tail use.
PSK is not FDA-approved in the United States as a cancer treatment.
Early human study Safety and tolerability only 11 recruited, 9 completed
Turkey Tail preparation after breast cancer treatment: phase I study
Nine women completed this early dose-escalation study. It was designed mainly to examine tolerability and immune measures, not whether Turkey Tail prevents recurrence or improves survival.
- What was studied
- Oral Trametes versicolor preparation at 3, 6, or 9 g/day for six weeks after radiation therapy
- Setting
- Not an efficacy study
- Why it ranks here
- The study provides early tolerability information but has no control group and is too small to evaluate cancer outcomes.
Limits and cautions
- Only nine participants completed the study.
- There was no placebo or untreated comparison group.
- Immune changes are not proof of improved cancer outcomes.
Turkey Tail products are not FDA-approved in the United States as a cancer treatment.