EFFECTS OF DIETARY FATTY-ACIDS ON BREAST AND PROSTATE CANCERS - EVIDENCE FROM IN-VITRO EXPERIMENTS AND ANIMAL STUDIES

Linoleic acid, an n-6 polyunsaturated fatty acid, is essential for nor mal mammary tissue development, at least in part because it provides t he metabolic precursor required for the biosynthesis of key eicosanoid s. A similar requirement applies to the growth of estrogen-independent but apparently not to estrogen-dependent rodent mammary and human bre ast carcinoma cells in vitro. By way of lipoxygenase products, n-6 fat ty acids also regulate expression of the invasive phenotype. High-fat, linoleic acid-rich diets promote chemically induced rat mammary carci nogenesis, virally induced mouse mammary tumor development, and the gr owth and metastasis of estrogen-independent human breast cancer cells in athymic nude mice. In contrast, saturated fatty acids have no disce rnible effects on mammary carcinogenesis or progression. Most mechanis tic studies have focused on the cyclooxygenase and lipoxygenase produc ts of n-6 fatty acid metabolism, and support is accumulating for inter actions between these eicosanoids and growth factors and oncogenes. Th e investigation of dietary fatty acids in prostate cancer is at an ear ly stage and has been handicapped by a lack of satisfactory animal mod els. However, there are indications that the n-6 fatty acids perform f unctions in experimental prostate cancer progression similar to those described for breast cancer.