The latest Cancer Council Australia figures for cancer rates in Australia show that one in three men and one in four women will be directly affected by cancer before the age of 75. And while more than half of the 88,000 new cases of cancer diagnosed in Australia each year will be successfully treated, cancer is still the leading cause of death in this country. The most common cancers in Australia (excluding non-melanoma skin cancer) are colorectal, breast, prostate, melanoma and lung cancer.

Traditionally, cancer treatment includes therapies such as chemotherapy, radiation therapy and surgery. However, all these therapies can have devastating side effects and they are not always successful. One of the most frequent causes of shortened survival time in cancer patients is metastasis, which is the spread of cancer cells from the primary site of the tumour to normal tissue elsewhere in the body via the bloodstream or lymph system. Although surgery can often successfully reduce the tumour mass, and chemotherapy or radiation therapy can sometimes further reduce the mass, these toxic therapies damage the immune system, and small clumps of malignant cells may survive despite best efforts to eradicate them.

Immunotherapy is another approach to cancer treatment whereby the body is revitalised to carry out its natural functions of eliminating abnormal tissues after its immune defences have been diminished by cancer and the toxic therapies used against cancer. Immunotherapy is also used in the treatment of allergies, HIV and other immune-related diseases.

What are mushroom immunoceuticals?

One class of immunotherapy yet to gain popularity in the West but commonly used in Asia is mushroom immunoceuticals. Immunoceuticals are dietary supplements that have an immune-boosting effect. They are used in conjunction with conventional cancer therapies to strengthen the body’s natural immune system ability.

Immunoceuticals obtained from certain mushrooms have become popular in Asia because they have been shown to lessen the adverse side effects of conventional therapies and assist in boosting the immune system to fight tumours. The Japanese Health and Welfare Ministry has approved three different anti-cancer drugs extracted from mushrooms: Lentinan, derived from Lentinus edodes; Schizophyllan, from Schizophyllum commune; and Polysaccharide-K (PSK), from Coriolus versicolor.

PSK, which is sold in Europe and Japan, is the best-selling anti-cancer drug in the world. In Japan, only 30 per cent of cancer treatment includes radiation, chemotherapy and/or surgery; that is, an individual with cancer is treated with 30 per cent traditional therapies and 70 per cent complementary therapies. More than 500 scientific papers over the past 30 years, predominantly from Japan, have looked at the anti-tumour and anti-bacterial effects of mushrooms. However, despite this research and Asia’s long history of using medicinal mushrooms, authorities in the West are still slow to move to human trials with such remedies.

The medicinal properties of mushrooms have been recognised in Asia for 2000 years. However, scientists have only been able to study the therapeutically active chemicals (immunoceuticals) of these mushrooms since the technological advances of the last 30 years. Once identified, these chemical substances have been isolated, concentrated and tested on animals, with more than 30 mushroom species showing anti-cancer action. However, only a handful of these have been taken to the next step and tested on humans. At this stage, the mushroom immunoceuticals with the most promise in helping fight cancers are Lentinan, Schizophyllan, Active Hexose Correlated Compound (AHCC), Maitake D-Fraction, Polysaccharide-K (PSK) and Polysaccharide-P (PSP).

But despite the lack of human clinical trials, there is a tremendous amount of data on the chemistry of mushroom immunoceuticals. In fact, what all these mushrooms have in common is their chemical structure. Research has shown that the most effective immunoceuticals are nearly always chemically defined as beta-glucans or proteoglycans. Beta-glucans are long polysaccharide chains with sugar molecules branching off the backbone of the chain, giving them a three-dimensional appearance. Proteoglycans are also long polysaccharide chains, but they have proteins rather than sugar molecules branching off the backbone of the chain. It is the branching side-chains that allow interaction with the receptors of various immune cells, thereby regulating their action. (At this stage, it is understood that the branching side-chains correlate with anti-cancer effects, but the precise mechanisms are not fully understood.) As a rule, proteoglycans have greater immune-boosting potential than beta-glucans.