ABSTRACT
Development of knowledge concerning the relationship between dietary fat and mammary carcinogenesis can be arbitrarily divided into three historical phases. The three historical phases are establishment of the fundamental tenet that dietary fat is an important determinant of mammary tumor development, demonstration that fat exerts its effects primarily on the promotion phase of carcinogenesis, and elucidation of mechanisms. In general, transplantable mouse mammary tumors are not hormone responsive and spontaneous mouse mammary tumors contain associated virus particles in contrast to rat mammary tumors, and human breast cancers. The origins and characteristics of each tumor model must be taken into consideration when evaluating the results of dietary experiments. An enhancing role for dietary polyunsaturated fatty acid has also been demonstrated in the transplantable mammary tumor model. The transplantable tumor model also has the disadvantage that tumor weight is the endpoint and that the difference between "stimulated" and "basal" growth is often numerically small.
