Her2 positivity in breast cancer refers to positivity for human epidermal growth factor receptor 2 on the surface of cancer cells. The full name of Her2 is Human Epidermal Growth Factor Receptor 2, which is a proto-oncogene that plays a key role in the cell growth factor signaling pathway. When the Her2 gene is highly expressed in cancer cells, large amounts of Her2 protein are produced on the cell membrane, which in turn stimulates the growth of cancer cells and increases their invasiveness. Breast cancer Her2 positivity suggests that the patient’s condition is more serious and prone to metastasis and recurrence. Patients with Her2-positive breast cancer may be considered for molecular targeted therapy. Trastuzumab and patuximab are the targeted drugs currently approved for Her2-positive breast cancer treatment. Adverse reactions such as dizziness and nausea may occur during the use of the drug, and patients should not take the drug on their own.