Reduction in mammary tumorigenesis in the rat by cabbage and cabbage residue

Mammary cancer was induced in female Sprague-Dawley rats by a single injection of N-methyl-N-nitrosourea (MNU) and rats were randomized to control fat (5%) and high fat (24.6%) diets. In addition, dried cabbage (5 and 10%) and collards (5%) were included in the diets of some animals. No statistically significant differences were observed in food consumption, body wt gain and caloric intake between the MNU-treated and control groups in the rats fed the low-fat diet. However, the groups fed the high-fat diet consumed more than the rats maintained on the control diet. The rats on the control fat diet containing cabbage exhibited a significantly lower incidence of mammary cancer than rats that were fed the control-fat diet without cabbage. This effect was not observed in comparable rats on the high-fat diet. The inhibitory effect on mammary tumorigenesis was demonstrated using a residue obtained from cabbage by exhaustive extraction with methanol, methylene chloride and petroleum ether. These studies reinforce the efficacy of cabbage as a 'suppressor' of cancer in experimental model systems under control-fat dietary conditions.