Neoadjuvant chemotherapy for breast cancer is a treatment method that has emerged only in the last two decades. Neoadjuvant chemotherapy was once called preoperative chemotherapy, first chemotherapy and induction chemotherapy, respectively. Since preoperative adjuvant chemotherapy is essentially adjuvant chemotherapy and its possible mechanism of action is different from general postoperative adjuvant chemotherapy, it is also customarily called neoadjuvant chemotherapy. The application of neoadjuvant chemotherapy for locally advanced breast cancer has been one of the standard treatment options internationally for more than 20 years, but it is relatively late in China. Why should neoadjuvant chemotherapy be applied to locally advanced breast cancer? First of all, we need to understand the concept of locally advanced breast cancer. Locally advanced breast cancer refers to breast cancer with tumor diameter greater than 5 cm, or multiple enlarged lymph nodes in the axilla on the same side and fused into a cluster, and no distant metastases can be detected on systemic examination. However, locally advanced breast cancer is usually difficult to treat because of late detection, and some of them are even closely adherent to the chest wall or have formed a large number of cancer plugs in the capillary lymphatic vessels of the local breast skin, resulting in breast skin edema, which is usually not directly operable in such cases. Meanwhile, studies have also found that the likelihood of micro-metastasis in liver, lung and bone marrow is much higher than 50% when such locally advanced breast cancer is detected. If radical breast cancer surgery is performed reluctantly for this type of locally advanced breast cancer, most patients will develop distant metastases or local recurrence soon after surgery. Therefore, neoadjuvant chemotherapy is the standard of care for these relatively advanced breast cancers, and has been the standard of care for patients with locally advanced breast cancer. Neoadjuvant chemotherapy can be simply interpreted as bringing forward the adjuvant chemotherapy after surgery to before surgery, but it produces results that cannot be achieved by post-surgical chemotherapy. Pre-operative neoadjuvant chemotherapy not only can effectively shrink huge primary breast cancer lesions and metastatic axillary lymph nodes, making surgical treatment of some locally advanced inoperable breast cancer possible, but also enables patients who cannot undergo breast-conserving surgery to undergo breast-conserving surgery after neoadjuvant chemotherapy, greatly improving the quality of life of patients with locally advanced breast cancer; neoadjuvant chemotherapy can also provide valuable neoadjuvant chemotherapy also provides valuable information on the chemotherapeutic sensitivity of tumors in vivo, thus also guiding postoperative adjuvant therapy; neoadjuvant chemotherapy has the effect of inhibiting the metastatic activity of tumor cells during surgery and the rapid growth of micrometastatic tumor cells after surgery, making the treatment of locally advanced breast cancer secure in all aspects and effectively improving the treatment outcome of these refractory breast cancers.