ABSTRACT
World-wide research has provided a number of theoretically and mechanistically sound and practically feasible means of prevention of important types of cancer in man. The mechanisms of carcinogenesis indicate that the introduction of cancer involves a stepwise sequence of distinct events. It begins with the transformation of normal cells by carcinogens that can be chemical, radiation, or viruses, affecting specific codons in DNA and representing a somatic mutation. Tobacco and tobacco smoke contain genotoxic carcinogens, but a major effect leading to cancer depends on promoting and enhancing elements. The question as to the nature of the genotoxic carcinogens for the important types of nutritionally linked cancers was open until fairly recently. At the Princess Takamatsu conference in 1976, Sugimura and associates mentioned for the first time the new finding of powerful mutagenic activity at the surface of fried fish or meat in Salmonella typhimurium TA98 and requiring metabolic activation with a liver S9 fraction.
