Role of dietary fatty acids in mammary gland development and breast cancer

Breast cancer is the most common cancer among women worldwide. Estimates suggest up to 35% of cases may be preventable through diet and lifestyle modification. Growing research on the role of fats in human health suggests that early exposure in life to specific fatty acids, when tissues are particularly sensitive to their environment, can have long-term health impacts. The present review examines the role of dietary fat in mammary gland development and breast cancer throughout the lifecycle. Overall, n-3 polyunsaturated fatty acids have promising cancer preventive effects when introduced early in life, and warrant further research to elucidate the mechanisms of action. (Author� abstract)

In this review article, the author�s provide an overview of the effects of fatty acids on  breast cancer (BC) which is one of the top five cancers contributing to overall cancer mortality worldwide. Evidence is reviewed which suggests that early life exposure to environmental factors such as diet may modify disease risk later in life. The n-6 fatty acids including linoleic acid (LA, 18:2n6) and arachidonic acid (AA, 20:4n6) are the two most common n-6 PUFA in typical western diets and have been suggested to have cancer-promoting effects. In contrast, n-3 PUFA may have anticancer effects. α-Linolenic acid (ALA, 18:3n3) is the predominant form of n-3 PUFA in western diets. The metabolism of ALA, involving sequential desaturation and elongation steps, gives rise to two important longchain n-3 PUFA: eicosapentaenoic acid (EPA, 20:5n3) and docosahexaenoic acid (DHA, 22:6n3). A growing body of research focusing on the role of diet in early life has emerged; in particular, on the consumption of specific fatty acids and cancer risk. The article describes the varying effects that dietary fatty acids have on mammary gland (MG) development and BC. There is inconsistency in the literature regarding the effects of specific classes of fatty acids and their role in BC. The lack of consensus may not be due to a lack of effect, but rather to a lack of understanding of temporal effects and of specific dietary fatty acids during critical periods of development. The authors note that the most promising research shows an ability of n-3 PUFA to alter MG development in the early stages of life, thus protecting against mammary tumorigenesis later in life. A better appreciation for diet during early life and critical periods of development may assist in providing clarity as to how best to conduct more rigorous human studies to ascertain the effect of dietary components in the development of BC. n-3 PUFA may have a beneficial role for both the prevention and treatment of BC as described in this article. The authors suggest that future research should focus on the effect of early n-3 PUFA exposure on long-term BC risk, targeting early development. The role of individual fatty acids in MG development and BC risk, specifically ALA enriched, EPA-enriched and DHA-enriched diets, is justified to elucidate differential effects. (Editor�s comments)