Diets high in fat have been demonstrated to enhance
carcinogenesis in numerous models. Studies on the relationship between
dietary fat and
cancer in experimental animals have improved with the evolution in our knowledge of the carcinogenic process and with our ability to formulate better controlled diets. This paper summarizes studies conducted during the past 15-20 years on the effects of
dietary fat on in vivo
carcinogenesis. Relationships between skin
carcinogenesis and
dietary fat have received little attention during this time, but tremendous progress has been made in our understanding of mammary and colon
carcinogenesis. Studies have been conducted of mammary
carcinogenesis induced in various rat strains by several chemical
carcinogens or by X-irradiation. Several colon
carcinogenesis models have also been used to evaluate
dietary fat effects. Recent studies in the lung, liver, and pancreas have shown relationships between the carcinogenic process at these sites and
dietary fat; however, further studies are needed. The confounding between high fat intakes and low
carbohydrate intakes and the difficulties of separating high fat intake from high caloric intake must be addressed in future research. The mechanism of the observed effects of
dietary fat is unknown.