Clinical studies in China showed polysaccharide extracts of Polyporus umbellatus to be as effective in preventing post-operative recurrence of bladder cancer as BCG (Bacillus Calmette-Guérin) and greater than Mitomycin C (MMC)40,41. One study of 313 patients after TURBT (transurethral resection of bladder tumour) or partial cystectomy who were followed up for 2 to 15 years (average 7.6 years) reported recurrence rates of 34.9% in the group receiving P. umbellatus polysaccharide extract, compared with 35.1% in the BCG group, 41.7% in the MMC group and 64.7% in the control group<sup>1</sup>.
In animal experiments P.umbellatus also inhibited the development of bladder cancer in rats exposed to N-butyl-N-(4-hydroxybutyl) nitrosamine with 11 of 18 animals staying cancer free. Polysaccharide extracts of Lentinula edodes, Grifola frondosa and Pleurotus ostreatus showed similar increases in host resistance with 9 of 17, 13 of 20 and 7 of 15 animals staying cancer free<sup>2</sup>.
In vitro studies with G. frondosa and Phellinus linteus extracts showed synergistic action with vitamin C against bladder cancer cell lines with non-cytotoxic doses of polysaccharide extracts becoming highly cytotoxic in combination with non-toxic levels of vitamin C<sup>3</sup>.
1. Prevention of postoperative recurrence of bladder cancer: a clinical study. Yang D, Li S, Wang H, Li X, Liu S, Han W, Hao J, Zhang H. Zhonghua Wai Ke Za Zhi. 1999;37(8):464-5.
2. Effects of Lentinus edodes, Grifola frondosa and Pleurotus ostreatus administration on cancer outbreak, and activities of macrophages and lymphocytes in mice treated with a carcinogen, N-butyl-N-butanol-nitrosoamine. Kurashige S, Akuzawa Y, Endo F. Immunopharmacol Immunotoxicol. 1997;19(2):175-83.
3. Effect of various natural products on growth of bladder cancer cells: two promising mushroom extracts. Konno S. Altern Med Rev. 2007;12(1):63-8.