PSK is one of the most commonly used medicinal mushroom extracts with a long history as an additive in cancer therapy in Asia, especially in Japan. PSK has adjuvant anti-tumor activity in vitro in various types of cancers, including colorectal, gastric, breast, liver, pancreatic, and lung cancer.[3]
Preliminary studies examining PSK include its use in conjunction with chemotherapy for colorectal cancer,[4][5] non-small cell lung carcinoma,[6] breast cancer,[7] liver cancer,[8] and leukemia.[9]
Chemistry
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.[10] 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.[11]
^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. PMID1735313. S2CID68080825.
^Hayakawa K, Mitsuhashi N, Saito Y, et al. (1997). "Effect of Krestin as adjuvant treatment following radical radiotherapy in non-small cell lung cancer patients". Cancer Detection and Prevention. 21 (1): 71–7. PMID9043766.
^Iino Y, Yokoe T, Maemura M, et al. (1995). "Immunochemotherapies versus chemotherapy as adjuvant treatment after curative resection of operable breast cancer". Anticancer Research. 15 (6B): 2907–11. PMID8669887.
^Suto T, Fukuda S, Moriya N, et al. (1994). "Clinical study of biological response modifiers as maintenance therapy for hepatocellular carcinoma". Cancer Chemotherapy and Pharmacology. 33 Suppl: S145–8. doi:10.1007/BF00686688. PMID8137477. S2CID25538345.
^Fisher M, Yang LX (2002). "Anticancer effects and mechanisms of polysaccharide-K (PSK): implications of cancer immunotherapy". Anticancer Research. 22 (3): 1737–54. PMID12168863.