Traditional anatomic pathological staging (e.g. TNM staging, including tumor size, number of lymph node metastases, and distant metastases) cannot be underestimated in predicting tumor recurrence and metastasis, and is a more mature clinical risk assessment index. However, since breast cancer is a heterogeneous tumor with great differences in histomorphology, immunophenotype, biological behavior and treatment response, the response to clinical treatment and prognosis of patients with the same traditional pathological TNM stage may be very different. In recent years, molecular typing of breast cancer based on DNA microarray technology and quantitative multi-gene RT-PCR assay to predict the risk of recurrence and metastasis of breast cancer and its response to treatment is often combined with molecular subtyping by gene microarray technology and immunohistochemistry, and the clinical application of ER, PR, HER-2 and Ki-67 can classify breast cancer into 4 types of molecular subtypes ( See table). Since the clinical response and survival of different molecular subtypes of breast cancer are very different, it is important to study the molecular markers and molecular typing of breast cancer to guide clinical treatment and prognosis. For example, the “triple-negative breast cancer” (ER, PR and HER-2 negative; Triple-negative breast cancer), which is clinically difficult to manage, corresponds to the Basal-like molecular expression (characterized by high expression of basal epithelial molecular markers). (CK5/6 or 17, EGFR) and low expression of ER or ER-related genes and HER-2 or HER-2-related genes), accounting for about 10% to 15% of all breast cancers. Triple-negative breast cancer has a 5-year survival rate of less than 15% and is often represented clinically as a type of breast cancer with a poor prognosis. Triple negative breast cancer is mostly seen in young premenopausal patients, with a higher chance of visceral metastasis and brain metastasis, poor histological grading, mostly grade 3, and a high proportion of proliferating cells with p53 mutation, positive expression of p53 and EGFR, and positive basal cell markers CK5/6 and CK17. The prognosis of triple negative breast cancer has little relationship with tumor size and lymph node status. Recurrence is rapid, with peak recurrence in 1-3 years and peak death in 5 years, with high incidence of brain metastasis and rapid development of distant metastasis leading to death. Endocrine therapy and trastuzumab (Herceptin) targeted therapy are ineffective in “triple negative breast cancer”, and the treatment relies on chemotherapy, which has poor sensitivity and is prone to drug resistance.