Effects of dietary fat on incidence of spontaneous and induced cancer in mice.

A study was done to evaluate the effect of quantity and degree of saturation of dietary fat on the incidence of spontaneous tumors in male and female Swiss mice and in female C3H mice and on the incidence of tumors induced by s.c. administration of 1,2-dimethylhydrazine (DMH) in Swiss mice. Diets contained 5 or 17% fat substituted isocalorically for sucrose in a semipurified diet. Gross autopsy results suggest that the quantity of dietary fat, when fed isocalorically, did not appreciably influence the incidence of spontaneous or DMH-induced tumors in these mouse strains. Mice fed 17% of the triene fat generally had a higher incidence of liver tumors than corresponding groups fed the saturated fat. High levels (0.5%) of butylated hydroxyanisole protected female C3H mice from spontaneous liver tumors, but low levels of butylated hydroxyanisole (200 ppm of fat) did not protect. Neither level of butylated hydroxyanisole influenced tumor incidence in CD-1 mice. The absence of gross bowel tumors in animals given DMH was unexpected but may be related to the levels of cholesterol and fiber in the diets, since these factors are reported to influence the effects of DMH.