Effects of the protein-bound polysaccharide preparation, PSK on spontaneous breast cancer in mice

The protein-bound polysaccharide preparation, PSK was tested for its ability to suppress carcinogenesis in spontaneous tumours in C3H/OuJ mice. They were divided into two groups of 40 individuals each. A normal diet was given to one group, establishing a control population, while the other group had 2% PSK added to their feed. Amount of feed consumed, body weight and tumour size were recorded weekly for 1 year. Within 15 weeks, 90% of the control population had developed tumours. In the test group the incidence of cancer and the number of tumours was significantly suppressed, and survival rates were improved. The amount of feed consumed and body weights of control and test groups were about the same.