For many many thousand years, mankind has been using various plants as nutrient, beverage, cosmetics, dye and medicine to maintain health and to improve quality of life. In Aisa, particularly, Panax ginseng C.A. Meyer is considered to be the most precious plant among herbs, and ginseng has been in the spotlight worldwide. Even in the Western world, where there are greatly advanced research facilities and highly qualified man-power available, and are regarded to be capable of conquering any hard-to-cure ailments, many peoples has recently been reported to use herbal medicine, particularly ginseng. In the present compilation of papers, many scientists contributed papers pertaining to "Chemopreventive effects of ginseng". In order to facilitate the readers understand easier and better, I catalogued this collection as follows: The spiritual nature of ginseng in the Far East, the history of ginseng, nomenclature and geographical distribution of ginseng, and type of ginseng products.

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 mediumterm 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.

In the light of experimental results, two case-control studies and one cohort study in a population of ginseng cultivation area were conducted to confirm whether ginseng has any anticarcinogenic effect on human cancers. All participants were interviewed using a standardised questionnaire to obtain the information on demographics, cigarette smoking, alcohol consumption and ginseng intake. In 905 pairs case-control study, 62% had a history of ginseng intake compared to 75% of the controls, a statistically significant difference (p<0.01). The odds ratio (OR) for cancer in relation to ginseng intake was 0.56. In extended case-control study with 1987 pairs, the ORs for cancer were 0.37 in fresh ginseng extract users, 0.57 in white ginseng extract users, 0.30 in white ginseng extract users, 0.30 in white ginseng powder users, and 0.20 in red ginseng users. Those who took fresh ginseng slices, fresh ginseng juice, and white ginseng tea, however, did not show decrease in the risk. Overall, the risk decreased as the frequency and duration of ginseng intake increased. With respect to the site of cancer, the ORs for cancers of the lip, oral cavity, pharynx, esophagus, stomach, colorectum, liver, pancreas, larynx, lung and ovary were significantly reduced by ginseng intake. Smokers with ginseng intake showed lower ORs for cancers of lung, lip, oral cavity and pharynx and liver than those without ginseng intake. In 5 yr follow- up cohort study conducted in the ginseng cultivation area, Kangwha-eup, ginseng intakers had significantly lower risk than non-intakers. As for the type of ginseng, cancer risk significantly decreased among intakers of fresh ginseng extract, alone or together with other ginseng preparations. Among 24 red ginseng intakers, no cancer death occurred during the follow-up period. The risk for stomach and lung cancers was significantly reduced by ginseng intake, showing a statistically significant dose-response relationship in each follow-up year. In conclusion, Panax ginseng C.A. Meyer has been established as non-organ specific cancer preventive, having dose response relationship. These results warrant that ginseng extracts and its synthetic derivatives should be examined for their preventive effect on various types of human cancers.

The objective of this investigation was to determine the efficacy of several novel agents in preventing lung tumorigenesis in mice. We evaluated polyphenon E, red ginseng, and rapamycin in A/J mice treated with the tobacco-specific carcinogen benzo(a)pyrene for their ability to inhibit pulmonary adenoma formation and growth. We found that treatment with polyphenon E exhibited a significant reduction on both tumor multiplicity and tumor load (tumor multiplicity x tumor volume) in a dose-dependent fashion. Polyphenon E (2% wt/wt) in the diet reduced tumor multiplicity by 46% and tumor load by 94%. This result provided key evidence in support of a phase II clinical chemoprevention trial of lung cancer. Administration of red ginseng in drinking water decreased tumor multiplicity by 36% and tumor load by 70%. The mammalian target of rapamycin inhibitor rapamycin showed significant efficacy against lung tumor growth in the tumor progression protocol and reduced tumor load by 84%. The results of these investigations demonstrate that polyphenon E, red ginseng, and rapamycin significantly inhibit pulmonary adenoma formation and growth in A/J mice.

While Panax ginseng C. A. Meyer has shown cancer-preventive effects both in experimental models and in epidemiological studies, the evidence is currently not conclusive as to its cancer-preventive activity in humans. The available evidence warrants further research into the possible role of ginseng in the prevention of human cancer and carcinogenesis.