Shiitake Mushroom Extract Does Not Help Men with Prostate Cancer
A shiitake mushroom extract is not effective in the treatment of prostate cancer, according to a recent preliminary study in Urology (2002;60:640–4).
Prostate cancer is the fourth most common cancer in men worldwide. It is the most common cancer and the second leading cause of cancer death in men in the United States. Conventional treatments for prostate cancer include surgery, radiation therapy, and medications that alter hormone activity. Sexual function is impaired in most men after each of these therapies. Other major side effects include urinary incontinence following surgery, fecal incontinence following radiation, and hormonal problems such as breast swelling and pain, hot flushes, and osteoporosis during medication therapy.
Due to the likelihood of long-term side effects which diminish quality of life, as well as the fact that prostate cancer usually progresses slowly over many years, doctors frequently postpone active treatment as long as possible, an approach known as "watchful waiting." This has led to a pressing search for natural approaches to stop or reverse the growth of prostate cancer. There is ample evidence that a number of nutritional factors influence an individual’s risk of developing prostate cancer. For example, nutrients such as selenium, vitamin E, isoflavones (phytoestrogens found in soy), and lycopene (an antioxidant found in tomatoes) appear to be preventive. Their usefulness in the treatment of prostate cancer remains largely unknown, although preliminary evidence suggests that lycopene may be beneficial. An herbal combination known as PC-SPES has also shown potential as anticancer agents for men with prostate cancer.
Shiitake mushroom (Lentinus edodes) is a major tonic in the Asian herbal pharmacy and has been used for thousands of years to treat a multitude of conditions. Many of its health benefits have been attributed to its positive effect on the immune system, borne out in animal and human trials. Promising results from a number of studies examining the effect of a shiitake mushroom extract on growth of cancer cells in test tubes and tumors in animals have led to interest in its potential anticancer properties in humans.
In the current preliminary study, 61 men with prostate cancer in various stages were given a shiitake mushroom extract for six months. The amount of mushroom extract given to each man was determined by body weight, based on a reference of 8 grams for a 150-pound man. Participants already receiving conventional therapies for their cancer continued them during the study. Prostate specific antigen (PSA), a marker in the blood for prostate cancer growth, was used in this study to determine response to treatment. Levels of PSA were measured before the trial and at one, two, four, and six months. At the end of six months, none of the participants had significant reductions in PSA levels, and 23 (38%) had increases of 50% or more. The researches concluded that shiitake mushroom extract has no benefit in the treatment of prostate cancer.
Studies have demonstrated anticancer properties of shiitake mushroom extract in animals with breast, colon, liver, and prostate tumors. The authors of the current study prepared their own shiitake mushroom extract and tested it on mice with prostate cancer before using it in the human trial. They observed significant reductions in tumor size in the treated mice, compared with untreated mice. A single case has been reported in which a man with prostate cancer experienced a drop in his PSA level and a full remission of his cancer after 44 days of treatment with a nutritional supplement composed of soy and shiitake extracts. The current study suggests that shiitake mushrooms by themselves are ineffective as a treatment for prostate cancer. Additional research is needed to determine whether shiitake mushrooms are beneficial when used as part of a comprehensive nutritional program.
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, Vermont, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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