Resumen
Breast cancer (BC) is a common malignancy with molecular diversity, i.e., heterogeneity. Aside from routine clinical treatments, such as chemotherapy and radiotherapy, which have side effects and tumor resistance, troubling patients and doctors, targeted therapy based on molecular classifications and immunotherapy with novel approaches to reprogram the immune system offer solutions to improve prognosis, anti-tumor efficacy, and address drug resistance. Here, we review the wide range of molecular classifications of heterogeneous BC, emphasize targeted therapy and immunotherapy, and provide insights into the significance of targeted drug delivery systems.