[BREASTFEEDING AS A METHOD OF BREAST CANCER PREVENTION].

INTRODUCTION: Breast cancer is the most common type or cancer in women with an incidence of about 720,000 cases per year and a mortality between 6 and 23 per 100,000, what it means a very important global health problem.

METHOD: Sistematic review in the following databases: PubMed, SciELO, Cochrane Plus, Medline, Cuiden and Embase. The search was limited to English and Spanish languages, between 2005 and 2015 and human studies.

RESULTS: All studies are observational by the characteristics of the studied pathology. It is observed that there is a decreased risk of breast cancer in women who had ever breastfed compared to those who had not. This reduced risk is most evident in postmenopausal women but also happens in premenopausal. It has also been observed that protection is increased with increasing lactation duration. The protective effect of breastfeeding happens by differentiation of breast cells, by reduction of the number of ovulatory cycles and by estrogen and carcinogens excretion through human milk. CONCLUSTONS: Breastfeeding is associated with a decreased risk of breast cancer, and health teams must therefore educate mothers about its beneficial effects to themselves and their children.