Strategy of research for cancer-chemoprevention

It has been reported that environmental chemicals are important factors in terms of both development and prevention of human cancer. For prevention of human cancer, detection of early cancer and clinical trials at the early stage have been focused so far. Now, next main project will be investigation for prevention of cancer development itself. Chemoprevention of carcinogenesis, which means prevention of carcinogenesis by some chemical compounds, have been investigated extensively in a variety of organs, but in only one organ. However, from results of our studies, antioxidants such as BHA, responded differently to organs, and whole body investigation, not only one organ carcinogenesis, should be performed to investigate of chemoprevention. Furthermore, the mechanisms of action of chemoprevention and on which step of carcinogenesis does the chemopreventive compound prevent, such as initiation, promotion, progression or whole carcinogenesis steps should be discussed. We have developed a medium term bioassay system and multi-organ carcinogenesis system, which can be used for investigation of cancer chemoprevention. Using these systems, we have investigated dose response inhibitory effects of BHA and α-tocopherol by the medium-term bioassay system, and catechins in the green tea inhibit small intestinal carcinogenesis in the multi-organ carcinogenesis. It is important for prevent human cancer to find other candidates for chemopreventive agents using animal study. (author)