Polyunsaturated fatty acids in breast cancer
Worldwide, breast cancer is one of the most common forms of cancer in women and in the last decade there has been an increase in newly diagnosed cases. In 2015, approximately 1.6 million new cases of breast cancer were diagnosed in women around the world. The incidence of this type of cancer seems to be higher in industrialised countries. According to the US National Institute of Statistics 90% of women are diagnosed when the disease is already advanced, thus significantly reducing the chances of survival and quality of life. The incidence of breast cancer has increased as a result of exposure to various environmental agents such as toxins, radiation and carcinogens, but epigenetic and genetic alterations can also arise from a unbalanced diet. The development and course of breast cancer are directly related to dietary habits and environmental exposure.
In western diets there is a predominance of processed food and vegetable oils with a high content of omega-6 polyunsaturated fatty acids (PUFAs) and low content of omega-3 PUFAs, which has significantly altered the proportion of these FA compared to that consumed by our ancestors (the ratio is estimated to have changed from 2:1 to 10:1). This has led to the appearance of disorders. For instance, the western diet is associated with oestrogen-receptor-negative breast cancer in women over 160 cm in height, and a comparison of normal breast tissue to neoplasm tissue shows that the latter has greater concentrations of omega-6 PUFA.
Both in vitro and in vivo studies have shown the tumour-suppressing effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). It is known that PUFAs play an important role in cellular and molecular processes, but the mechanism by which omega-3 exercises its anti-cancer actions are not completely clear; nor is the mechanism underlying the carcinogenic effect of omega-6.
Dietary factors are recognised as influencing activation of carcinogenic events in the progression of the disease and it is know that they are directly connected to preventing breast cancer. Omega-3 PUFAs differentially inhibit the development of breast tumours, modifying the morphology of the cell membranes and influencing their signalling, genetic expression and apoptosis. Observation of the molecular mechanisms involved suggest that, under medical supervision, dietary supplements should be administered in combination with antineoplastic agents.
Most studies recommend that patients follow a diet rich in omega-3 PUFAs and reduce consumption of omega-6. And changing dietary habits, particularly with regard to fats, could be used as a strategy to prevent breast cancer.
Zanoaga O Jurj A, Raduly L, et al. Implications of dietary ω-3 and ω-6 polyunsaturated fatty acids in breast cancer. Exp Ther Med. 2018;15(2):1167-76. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5776638/