Polysaccharide-K (PSK)
What is Polysaccharide-K (PSK)?
Polysaccharide-K (PSK) or krestin, from the mushroom T. versicolor, is an approved mushroom product used for cancer treatment in Japan. PSK is a proprietary formulation from the Kureha Corporation. PSK has been used as an adjunctive cancer treatment in thousands of patients since the mid-1970s. The safety record for PSK is well established in Japan.
National Cancer Institute
Preventing Surgery-Induced Immune Suppression
Source: Life Extension Magazine
The essential role the immune system plays in combating cancer cannot be overstated. Although there are many aspects of the immune system that come into play when fighting cancer, the role of the natural killer cell predominates. Natural killer (NK) cells are a type of white blood cell tasked with seeking out and destroying cancer cells. Research has shown that NK cells can spontaneously recognize and kill a variety of cancer cells.
To illustrate the importance of NK cell activity in fighting cancer, a study published in the journal Breast Cancer Research and Treatment examined NK cell activity in women shortly after surgery for breast cancer. The researchers reported that low levels of NK cell activity were associated with an increased risk of death from breast cancer. In fact, reduced NK cell activity was a better predictor of survival than the actual stage of the cancer. In another alarming study, individuals with reduced NK cell activity before surgery for colon cancer had a 350% increased risk of metastasis during the following 31 months!…
…One prominent natural supplement that can increase NK cell activity is PSK, (protein-bound polysaccharide K) a specially prepared extract from the mushroom Coriolus versicolor. PSK has been shown to enhance NK cell activity in multiple studies. PSK’s ability to enhance NK cell activity helps to explain why it has been shown to dramatically improve survival in cancer patients. For example, 225 patients with lung cancer received radiation therapy with or without PSK (3 grams per day). For those with more advanced Stage 3 cancers, more than three times as many individuals taking PSK were alive after five years (26%), compared to those not taking PSK (8%). PSK more than doubled five-year survival in those individuals with less advanced Stage 1 or 2 disease (39% vs.17%).
Read the full article at Life Extension Magazine
Results of Studies
The findings of this study were summarised as follows:
PSK is currently used as an immunothenapeutic agent for gastric, colorectal, and lung cancers in Japan. It has virtually no adverse effects, and it can be administered over a long term. Consequently, its use need not be limited to the treatment of cancer, and, as our previous paper suggested, it should in the future prove valuable as a general chemo-preventive agent and, as this review shows, as an anti-metastatic agent. The principal mechanisms of PSK may act as an inhibitor of the motility, invasion, and progression of tumor cells, in addition to its mole as an immune-modulator.
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Polysaccharide-K (PSK, Krestin®), one of the most commonly used medicinal mushroom extracts, has documented anticancer activity both in vitro and in human clinical trials…It was approved as a therapeutic agent for the treatment of cancer and has been widely used in Japan and other Asian countries. By 1987, PSK accounted for more than 25% of the total national expenditure for anticancer agents in Japan, says this study.
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This study To evaluate the efficacy of Krestin (PSK) as adjuvant treatment after radical radiation therapy (RT) for non-small cell lung cancer (NSCLC), treatment results of 225 patients with NSCLC treated with RT followed by adjuvant administration of PSK between 1976 and 1989 were analyzed. Of these patients, 170 (76%) had squamous cell carcinoma. In the patients with squamous cell carcinoma of the lung, PSK was given only when the tumor showed satisfactory shrinkage (complete or partial response) after completion of RT. The treatment outcomes were compared with those of the responders to RT not receiving PSK. The 5-year survival rates of patients with stages I-II and stage III disease were 39 and 26%, respectively, while the non-administered responder group’s were 17 and 8%. These differences are statistically significant.
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This study says:
Several randomized clinical trials have demonstrated that PSK has great potential as an adjuvant cancer therapy agent, with positive results seen in the adjuvant treatment of gastric, esophageal, colorectal, breast and lung cancers. These studies have suggested the efficacy of PSK as an immunotherapy or biological response modifier (BRM). BRMs potentially have the ability to improve the “host versus tumor response,” thereby increasing the ability of the host to defend itself from tumor progression…PSK has further been shown to have antioxidant capacity which may allow it to play a role as a normal tissue chemo- and radio-protector when used in combination with adjuvant or definitive chemotherapy and/or radiotherapy in the treatment of cancer, while it may also enable it to defend the host from oxidative stress. Interestingly, studies have also shown that PSK may actually inhibit carcinogenesis by inhibiting the action of various carcinogens on vulnerable cell lines. This action of PSK may play a role in preventing second primary tumors when an inducing agent, such as tobacco or asbestos, is suspected and may also prevent second malignancies due to the carcinogenic effects of radiotherapy and cytotoxic chemotherapy.
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This Review of lung cancer studies says:
Fifteen of 17 preclinical studies supported anticancer effects for PSK through immunomodulation and potentiation of immune surveillance, as well as through direct tumor inhibiting actions in vivo that resulted in reduced tumor growth and antimetastatic effects. Nonrandomized controlled trials showed improvement of various survival measures including median survival and 1-, 2-, and 5-year survival. Randomized controlled trials showed benefits on a range of endpoints, including immune parameters and hematological function, performance status and body weight, tumor-related symptoms such as fatigue and anorexia, as well as survival.
Adverse Reactions
Coriolus versicolor is generally well tolerated, but a few adverse reactions have been reported when it was used in conjunction with chemotherapy. They include passage of dark-colored stools (not originating from occult blood), darkening of fingernails, and low-grade hematologic and gastrointestinal toxicities.
Herb-Drug Interactions
No known interactions between Coriolus versicolor and prescription medications have been reported.
(Source: ASCO Post)
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