The Effect of Dietary n-3 Polyunsaturated Fatty Acids on Non-obese and Obesity-Associated Breast Cancer

Globally, breast cancer is the most diagnosed type of cancer in females, wherein almost half of all breast cancer will develop some form of metastatic disease. Lifestyle factors including diet and physical activity are estimated to prevent between 20% and 40% of all types of cancer; therefore, identifying dietary components that reduce breast cancer risk and/or severity is highly relevant. Long-chain n-3 polyunsaturated fatty acids (PUFA) derived from marine dietary sources including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to attenuate mammary carcinogenesis. In this chapter we will evaluate and review the literature identifying the relationship between dietary n-3 PUFA (as fish and fish oil, individual fatty acids or combinations of n-3 PUFA) and breast cancer in human, animal model, and cell culture studies with a discussion of underlying mechanisms of action. Additionally, we will examine the effectiveness of dietary n-3 PUFA to attenuate obesity-associated breast cancer, whose prevalence is increasing in tandem with the increasing prevalence of obesity. Obese breast cancer patients typically experience lower rates of survival, greater treatment complications and a more aggressive clinical course. Thus, the combined anti-inflammatory and anti-carcinogenic effects of n-3 PUFA may have utility in attenuating severity of both non-obese and obesity-associated breast cancer.