Do all breast cancer patients need targeted therapy? Of course, the answer is no. Targeted therapy is a treatment that targets cell receptors, key genes and regulatory molecules. Targeted therapy is a treatment that targets cellular receptors, key genes and regulatory molecules, and is another effective treatment after surgery and radiotherapy. The targeted therapy mentioned in breast cancer generally refers to the use of Herceptin or trastuzumab, which targets Her-2 gene. Her-2 receptor is a member of the epidermal growth factor family, a transmembrane protein with tyrosine kinase activity, encoded by the Her-2 gene, which is overexpressed in 20%-30%; of advanced breast cancer tissues. Trastuzumab, Herceptin, is an antibody against Her-2 receptor, which mainly acts on Her-2 receptor overexpressed tumor cells. It binds to the extracellular region of the receptor, interferes with the autophosphorylation of tumor cells and the formation of heterodimers, inhibits the activation of signaling system, and thus affects the proliferation of tumor cells. Herceptin is mainly used in patients with invasive breast cancer partially detected by IHC for Her-2+++ or FISH for Her-2 gene amplification. Studies have shown that the application of targeted therapy can reduce the risk of recurrence and metastasis and improve disease-free survival and overall survival in this group of patients, but there is no significant significance for cases without Her-2 gene overexpression. And studies have shown that the optimal duration of Her-2 use in this group of patients is 1 year, and there is no clear evidence that using it for shorter or longer than 1 year has a benefit on disease-free survival or overall survival of patients. Of course, Herceptin has its side effects, and the most serious adverse effects known so far are mainly cardiotoxicity, so it is generally not recommended to combine Herceptin with anthracyclines because Herceptin can affect the metabolism of anthracyclines, and anthracyclines are also cardiotoxic, thus aggravating this adverse effect. In recent years, several new targeted therapeutic agents have been developed for different targets, but their efficacy and safety have yet to be further confirmed in clinical studies. However, there is no doubt that targeted therapy will become an important therapeutic modality in the future with the prospect of molecular biology.