Protective effect of dietary brussels sprouts against mammary carcinogenesis in Sprague-Dawley rats

The effect of dietary brussels sprouts (Brassica oleracea, L.) on mammary carcinogenesis induced by 7,12-dimethylbenz[a]anthracene (DMBA) was studied in Sprague-Dawley female rats. Rats fed a 20% brussels sprouts diet only during the initiation period of carcinogenesis had a palpable mammary tumor incidence of 13%, while those fed a casein-cornstarch semi-purified diet during this initiation period had a tumor incidence of 77% after 15 weeks post DMBA dose. When the rats were switched from the semi-purified diet to the 20% brussels sprouts diet at this time, there appeared to be a regression of small mammary tumors after 6 weeks on this dietary treatment. This regression was transitory since during the final 10 weeks of this 1 year study, 100% of this group of rats developed tumors. The rats fed the 20% brussels sprouts diet during tumor initiation exhibited a 67% incidence of fibroadenomas. The rats fed the semi-purified diet during initiation, but switched later to the brussels sprouts diet, showed over a 90% incidence of adenocarcinomas.