Breast cancer is the most frequent type of cancer in women in the world. In Mexico, since 2006, this disease has become the leading cancer-related cause of death in women. It is estimated that incidence and mortality will continue to rise due to population aging, to changes in reproductive patterns, to a higher prevalence of risk factors and to limited access to medical care, resulting in delayed early diagnosis and timely treatment. The latter factors are the ones to improve in developing countries to decrease the high incidence and mortality associated with this disease. Recently, there is a great interest regarding breast cancer heterogeneity, and it is anticipated that the application of new technologies will improve our comprehension of this disease and will be reflected in a benefit for patients in the short term. Here, we review updated information on molecular diagnosis and therapeutics, as well as recent highlights in the biology of breast cancer.