Alpha-linolenic acid, anti-oxidants and the growth of breast tumours

International variation in breast cancer incidence rates and the changes in incidence among migrant populations have indicated that breast cancer risk is influenced by environmental factors, in particular diet, and is therefo re preventable. Data derived from animal experiments generally showed that diets high in n-3 polyunsaturated fatty acids (PUFA) inhibit mammary tumor growth and metastasis. Limited data is available on the relation of estimat ed dietary intake of n-3 PUFA to risk of breast cancer. We confronted adipose tissue fatty acid composition, as a reflect of long-t erm, qualitative dietary intake of fatty acids, to the risk of metastasis i n patients treated for breast cancer and we reported an inverse association between level of alpha-linolenic acid, essential fatty acid, and the devel opment of metastasis, suggesting a protective effect of alpha-linolenic aci d in the evolution of breast cancer. In two independent case-control studie s conducted in women treated for breast tumours, we found on inverse associ ation between alpha-linolenic acid in adipose fat and breast cancer risk, s uggesting a protective effect of this fatty acid in the risk of the disease . In experiments performed in a model of chemically-induced rat mammary tum ors, we examined the role of alpha-linolenic acid and peroxidation processe s on mammary tumor growth. We found that tumor growth was increased by a 15 % linseed oil diet, rich in alpha-linolenic, in presence of antioxidant (vi tamin E) while was decreased by alpha-linolenic acid in presence of a pro-o xidant system. These data show that the effect of alpha-linolenic acid on t umor growth is highly dependent on diet oxidative status. Further epidemiol ogical and experimental studies are needed in order to identify the interac tion of n-3 PUFA with anti- and pro-oxidative vitamins in the risk of breas t cancer.