Lípidos de la dieta y cáncer de mama: evidencias científicas clínicas, anatomopatológicas y moleculares.

Breast cancer is the most common cancer in women worldwide. The great geographical differences in the incidence rates of this neoplasia suggest that, besides genetic and endocrine, environmental factors should also be involved in its development. Among them, the nutritional ones are the most remarkable. A number of epidemiological and experimental studies have demonstrated the relationship between dietary lipids and breast cancer. The results of the epidemiological studies are controversial. Thus, whereas the ecological studies support this relation, in case-control and prospective cohort studies the evidence is less consistent. However, experimentally it has been demonstrated that the type and quantity of lipids, besides the timing of their administration, play a key role in the promotion of the mammary carcinogenesis and, even, in its initiation. Linoleic acid (18:2n-6) is one of the stimulatory fatty acids and is found in high quantity in vegetable oils, as corn and sunflower oils. Olive oil, the main source of fat in Mediterranean diet, is rich in oleic acid (18:1n-9) and several minor bioactive compounds, and could exert a protective role. In an experimental mammary cancer model, we have demonstrated that diets rich in virgin olive oil exert from a negative modulatory role, likely protective, of the mammary carcinogenesis to a weak promoting effect, very lower to that obtained with high corn oil diets. Olive oil not only confers to the mammary adenocarcinomas a clinical behaviour compatible with a lower biological aggressiveness, but also morphological features of greater benignity. These actions are carried out through several mechanisms, among which changes in the composition and function of cell membranes, activity of signalling proteins and specific gene expression point out. In this way, the distinct dietary lipids would modulate differentially the proliferation and differentiation status of breast tumours.