PSK is isolated from the fruitbody of Trametes versicolor. Preliminary evidence indicates PSK has anticancer activity in vitro, in vivo and in human clinical trials. Preliminary research has also demonstrated that PSK may inhibit various cancer onset mechanisms. Preliminary evidence indicates PSK may have use as an adjuvant in the treatment of gastric, esophageal, colorectal, breast and lung cancers. Human clinical trials suggest PSK may affect cancer recurrence when used as an adjuvant, and basic research has demonstrated it inhibited certain human cancer cell lines in vitro.
The MD Anderson Cancer Center reported that it is a "promising candidate for chemoprevention due to the multiple effects on the malignant process, limited side effects and safety of daily oral doses for extended periods of time." The Therapeutic Goods Administration in Australia reported that the WHO has only eight records of adverse effects with PSK and none reported for PSP.
In conjunction with chemotherapy, PSK has increased the survival time of cancer patients in randomized, control studies, with stomach cancer (meta-analysis of 8,009 patients), colorectal cancer (randomized, controlled study of 448 patients), non-small cell lung carcinoma,[unreliable medical source?] and small cell carcinoma of the lungs. PSK has produced mixed results with breast cancer,[unreliable medical source?] liver cancer, and leukemia.[original research?]
PSK is a protein polysaccharide consisting of a beta-glucan β-1,4 main chain with β-1,3 and β-1,6 side chains. The approximate molecular weight of PSK is 100,000 Da, and the protein component is reported at the β-1,6 side chain. PSK is isolated from the "CM-101" strain of Trametes versicolor. The analogous compound PSP, is derived from the "COV-1" strain of Trametes versicolor.
- Jiménez-Medina E, Berruguilla E, Romero I et al. (2008). "The immunomodulator PSK induces in vitro cytotoxic activity in tumour cell lines via arrest of cell cycle and induction of apoptosis". BMC Cancer 8: 78. doi:10.1186/1471-2407-8-78. PMC 2291471. PMID 18366723.
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- Hsieh TC, Wu JM (January 2001). "Cell growth and gene modulatory activities of Yunzhi (Windsor Wunxi) from mushroom Trametes versicolor in androgen-dependent and androgen-insensitive human prostate cancer cells". International Journal of Oncology 18 (1): 81–8. doi:10.3892/ijo.18.1.81. PMID 11115542.
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- "Coriolus versicolor". Complementary and alternative therapies for cancer patients. San Diego: University of California.
- Mitomi T, Tsuchiya S, Iijima N, et al. (February 1992). "Randomized, controlled study on adjuvant immunochemotherapy with PSK in curatively resected colorectal cancer. The Cooperative Study Group of Surgical Adjuvant Immunochemotherapy for Cancer of Colon and Rectum (Kanagawa)". Diseases of the Colon and Rectum 35 (2): 123–30. doi:10.1007/BF02050666. PMID 1735313.
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- Ohno R, Yamada K, Masaoka T, et al. (1984). "A randomized trial of chemoimmunotherapy of acute nonlymphocytic leukemia in adults using a protein-bound polysaccharide preparation". Cancer Immunology, Immunotherapy 18 (3): 149–54. doi:10.1007/BF00205503. PMID 6391658.
- American Cancer Society's page for Trametes versicolor and Polysaccharide-K.
- Memorial Sloan-Kettering Cancer Center's page for Trametes versicolor and Polysaccharide-K.
- A "Detailed Scientific Review of Trametes versicolor and Polysaccharide-K" by the MD Anderson Cancer Center.
- Trametes versicolor and Polysaccharide-K information from Drugs.com.