The failure to improve the five-year survival rate of
cancer patients, from one in three in the 1960s to one in two in the 1970s, stimulated awareness of the importance of primary prevention of
cancer. Korean investigators carried out extensive long-term anticarcinogenicity experiments with 2000 newborn mice to investigate whether Panax ginseng C.A. Meyer inhibited
carcinogenesis induced by several chemical
carcinogens in 1978. There was a 22% decrease (p<0.05) in the incidence of
urethane induced lung
adenoma by the combined use of red ginseng extract. In the group sacrificed at 56 weeks after the treatment with
aflatoxin B1, the incidence of
hepatoma significantly decreased to 75% by the addition of red ginseng extract (p<0.05). The result showed that natural products can provide hope for human
cancer prevention. By the newly established '9 week medium-term anticarcinogenicity test model of lung
tumors in mice' (Yun's model), we confirmed significant
anticarcinogenic effects of powders and extracts of the 6- yr-old dried fresh ginseng, 5- and 6-yr old white ginsengs, and 4-, 5-, and 6-yr old red ginseng. We also demonstrated that the anticarcinogencity of ginseng was more prominent in aged or heat treated extracts of ginseng and red ginseng made by steaming. To investigate the active components for
cancer prevention, several fractions of 6-yr old fresh ginseng and red ginseng, four semi-synthetic
ginsenoside Rh1, Rh2, Rg3 and Rg5, major
saponin components in red ginseng, were prepared. Among the
ginsenosides, Rg3 and Rg5 showed statistically significant reduction of lung
tumor incidence and Rh2 had a tendency of decreasing the incidence.
Ginsenoside Rg3, Rg5 and Rh2 were found to be active anticarcinogenic compounds. Rg3, Rg5 and Rh2 are active components in red ginseng, and they prevent
cancer either singularly or synergistically.