ERBB2 and breast cancer: Because of the further understanding of pathogenesis, more signaling pathways have been found, and, correspondingly, therapeutic targets in breast cancer, such as hormone receptor, HER-2, epidermal growth factor receptor, and vascular endothelial growth factor, which optimize the accuracy of antitumor activity and minimize toxicity to normal tissues, play a crucial role in breast cancer treatment in the era of precision medicine (35, 36).