Asian studies of cancer chemoprevention: latest clinical results.

Chemoprevention trials in Asia, including those already completed and those now ongoing, are reviewed. Information was mainly collected from Japan, Korea and China. Each country features its own characteristics. Cancer chemoprevention trials targeting, from various aspects, hepatocellular carcinoma, gastric cancer and colon cancer have been, and are now being, conducted in Japan. Japan also has a long history of basic carcinogenesis research and carcinogenic research using animal experiments. In Korea, ginseng is the main focus of studies of chemopreventive agents. A large body of information has been collected and prospective studies are also ongoing. In China, the Linxian study, a cooperative study participated in by China and the NCI of the USA, is well known and the results impressive. However, we must exercise caution because, for example, the population of Linxian are chronically deficient in multiple vitamins and trace minerals. This situation may, therefore, differ from that observed in other countries. In any event, chemoprevention studies will be popular from an economical point of view even in Asia because cancer is becoming the number one cause of death in these countries.