There has been much scientific interest in fungi for cancer care in recent years, and for good reason. This article shares some of the research in this fascinating branch of oncology and herbalism.

The demand for medicinal mushrooms has been gradually growing and is expected to continue doing so in the next decade (1). With increasing research, the general public is becoming more and more aware about the health benefits of these fascinating members of the fungal kingdom. 

Medicinal mushrooms have been used in East Asia for thousands of years, with records of this being left in the Chinese herbal book Shen Nong Ben Cao, which dates to 200AD (2). Medicinal mushrooms are still used within traditional Chinese medicine (TCM) as part of the mainstream medical system in China (3). The anti-tumour properties of mushrooms have been extensively researched in Japan, where the active constituent of shiitake is used intravenously in conventional treatment protocols (2). 

Mushrooms are neither plants nor animals, they belong to a completely different category: the fungal kingdom. Mushrooms are metabolically closer to animals but structurally closer to plants. Both plants and mushrooms have a cell wall formed by long chains of sugar molecules called polysaccharides. The long sugar (glucose) chain in plant cell walls is called cellulose. In mushrooms, the structure of these long glucose chains is slightly different to cellulose, as it has side chains attached to the main chain, making it a more complex structure. These mushroom polysaccharides or complex glucose chains are responsible for many of mushroom’s health benefits, including immunomodulatory effects and anti-tumour activity (2).

Some fungi are composed of a network of thread-looking long chains growing underground, called the mycelium or mycelial network, and a visible fruiting body, the so-called mushroom. Mushrooms are the visible part of fungi, and they are responsible for producing spores and helping fungi reproduce. Mushrooms are fungi’s reproductive organs, as they bear the spores the fungus will use to spread and propagate itself (4).

The main biologically active compounds found in mushrooms with an anti-tumour and immunomodulatory action are the polysaccharides and triterpenes. Polysaccharides are water-soluble and triterpenes are alcohol or ethanol-soluble. Some research has suggested that the degree of anti-tumour activity is related to the degree of branching and solubility of the polysaccharides. The more branching, the higher the anti-cancer activity in vitro (5). 

Mushrooms trigger a wide range of immunological changes that are useful in having an anti-cancer effect. Some of these changes include the following (2): 

• Increase in natural killer (NK) cells
• Increase cytotoxic T-cell activation
• Decrease pro-inflammatory cytokines
• Apoptosis of cancer cells

Some mushrooms such as turkey tail have also been shown to minimise chemotherapy side effects, being helpful when taken concomitantly with conventional treatment.

Almond mushroom (Agaricus subrufescens)

This mushroom is originally from Brazil but has been widely used in Japan, as a farmer of Japanese descent living in Brazil sent some spores to Japan in the 1960s. It is reported to being taken by 31% of patients with urological cancers in Japan (2).

The polysaccharides in almond mushrooms have been shown to have strong activity in vitro and in vivo against different cancer cell lines. This mushroom is particularly good when used synergistically with chemotherapy and radiotherapy (6). Not only has it been shown to improve the efficacy of chemotherapy or radiotherapy when used in combination, but it is also effective at decreasing the side effects of chemotherapy such as appetite loss, alopecia, generalised weakness and emotional instability (7). There are a couple of clinical studies reporting almond mushroom taken daily as a tea increases red cell production and quality of life in patients receiving chemotherapy for acute non-lymphocytic leukaemia and late-stage gastrointestinal cancers (8).

Almond mushroom has also been shown to significantly increase NK cells in both, human volunteers (9), and also in patients with cervical, ovarian and endometrial cancer being treated with chemotherapy (10).

Cordyceps (Cordyceps sinensis)

Cordyceps is a very interesting mushroom that in the wild grows through an insect host, either parasitically or in symbiosis. Cultivated cordyceps however mostly grows on grain-based substrates instead of insects (2).

Cordyceps containing polysaccharides have significant immune-modulating properties that are useful in cancer care. It also contains molecules called nucleoside derivatives (similar to the component parts of DNA). One of the most widely researched nucleosides in cordyceps with anti-tumour properties has been cordycepin (11). Cordycepin has been found to induce apoptosis (or what is the same, induce death of cancer cells) and to improve treatment outcomes in different cancer types such as in oral, colorectal, bladder, leukaemia, melanoma, multiple myeloma, breast and prostate (12, 13).

Cordyceps is however contraindicated in hormone-dependent cancers such as breast cancer or prostate cancer when these are hormone-driven. This is because cordyceps can increase levels of sex hormones levels (i.e., oestrogen and testosterone), and therefore should not be used in hormone-dependent cancers (2). As cordyceps can be useful in bringing down glucose levels, it should be used with caution by people taking insulin to avoid unwanted hypoglycaemic episodes.

Turkey tail (Trametes versicolor)

Turkey tail is the most widely researched mushroom for cancer care and is used alongside conventional treatment in China and Japan. Turkey tail has been traditionally used to improve immune function and has a long traditional use for tumours. The two polysaccharides that have been studied in large-scale clinical trials are PSK and PSP (2).

The polysaccharide PSK in turkey tail can be beneficial for cancer care through numerous mechanisms. It has been shown to increase immune cell production and improve the immune status of the patient, which enables them to fight cancer cells off more efficiently (14). It can increase cytotoxic T cells, which are immune cells that can destroy cancer cells (14). PSK has also been shown to increase survival in certain cancers (oesophageal, gastric, colorectal, nasopharynx, lung and uterine) (15). For example, in patients with advanced gastric cancer, PSK doubled 2-year survival rates when given alongside chemotherapy and surgical intervention, and in patients with colorectal cancer, it improved 8-year survival (15).

A meta-analysis confirmed that turkey tail increased survival and that it also significantly reduced chemotherapy and radiotherapy side effects (16). Turkey tail is therefore a promising mushroom that can be used to support patients with cancer when the right preparation is used. 

Maitake (Grifolia frondosa)

Maitake is another mushroom with potent anti-cancer properties. Polysaccharides are the main active constituents of maitake, specifically the isolated D-fraction and MD-fractions. These have potent immunomodulatory and anti-tumour actions (17).

Maitake MD-fraction used in combination with the fruiting body showed improvement of disease progression and an increase in immunocompetent cells in 58% of liver cancer patients (7 of 12), 68% of breast cancer patients (11 of 16) and 62% of lung cancer patients (5 of 8) (18). It was a small study, however these results still warrant attention for the Maitake mushroom as a potential candidate for cancer support as well as further research into its anti-tumour properties.

Other studies have confirmed amelioration of chemotherapy side effects such as loss of appetite, nausea, vomiting, alopecia, and leukopenia (2).

Reishi (Ganoderma lucidum)

Reishi is a well-known mushroom whose properties and reports of its medicinal use can be found in Chinese literature dating back to 200 AD. We now know that reishi has a wide range of actions, many of them relevant in cancer care as it is an anti-inflammatory, immunomodulator, it increases cytotoxic T cells, and it induces apoptosis. The main constituents responsible for reishi’s therapeutic actions are polysaccharides and triterpenes (2).

Polysaccharides are immunomodulators, increasing Th1 cytokine levels including NK cells and decreasing Th2 cytokine levels (19). There have been several randomised clinical trials indicating that patients taking polysaccharide preparations of reishi were 1.37 times more likely to have a positive response to chemo or radiotherapy (2).

Triterpenes have shown a significant cytotoxic activity against cancer cell lines, and potent inhibition of NF-kappaB nuclear transcription factor (20). NF-kappaB is overexpressed in some cancer cell lines, allowing cancer cells to survive and spread. Reishi’s triterpenes inhibiting this transcription factor is another useful anti-tumour mechanism of action. Triterpenes in Reishi have been shown to specifically promote cell death and inhibit cancer cell growth of prostate cancer cells by blocking androgen receptors (21).

Polysaccharides are water-soluble and triterpenes are ethanol soluble, so this is an important consideration to take into account when preparing commercial Reishi for therapeutic purposes. 

Reishi’s triterpenes have been reported to have anti-coagulant effects, so people taking blood-thinning or anticoagulant medications should be monitored and take reishi with caution (2). Reishi is not contraindicated in pregnancy but because of this anticoagulant effect it should be taken with caution during pregnancy and it is best to work with a practitioner if you want to take reishi when pregnant.  

Shiitake (Lentinula edodes)

Shiitake is yet another well-known mushroom widely used for culinary purposes. It is very nutritious as it contains high levels of B vitamins, and is a good source of vitamin D2 if exposed to sunlight or IV light before or after harvesting (22).

The main active constituents of shiitake are the polysaccharide lentinan as well as other polysaccharides. Lentinan containing shiitake has been used in Japan for centuries for cancer care, but the anti-tumour properties of lentinan were first reported in 1960s by Japanese researchers. Most trials have studied the effect of lentinan given intravenously, but it appears to also have good orally bioavailability, although therapeutic oral doses will need to be higher (2).

Different trials have shown increased survival, improved quality of life and reduced chemotherapy side effects in patients with oesophageal, hepatocellular, colorectal, breast and metastatic prostate cancer (23). Furthermore, lentinan increased survival in several studies when used in combination with chemotherapy in advanced gastric cancer (24).