The basic structure of TNM staging is based on the size of the tumor (T for short), whether the lymph nodes are metastatic and the number of metastases (N for short), and whether there are distant organ metastases (M for short), etc. The value of TNM for predicting the recurrence and metastasis of the tumor cannot be underestimated and is a more mature risk assessment index in clinical practice. . Primary tumor (T) staging: Tx primary tumor status unknown (resected). t0 primary tumor not retrieved. tis carcinoma in situ (including lobular carcinoma in situ and intraductal carcinoma), Paget’s disease confined to the nipple, no masses retrieved in the breast. t1 tumor maximal diameter less than 2Cm. t2 tumor maximal diameter 2-5crn. t3 tumor maximal diameter more than 125px. t4 tumor of any size. Direct invasion of chest wall and skin (including inflammatory breast cancer). Regional lymph node (N) staging: N0 regional lymph nodes are not found; Nx regional lymph nodes are unknown (previously excised). N1 ipsilateral axillary lymph nodes are enlarged and mobile. N2 ipsilateral axillary lymph nodes are enlarged, fused with each other or adherent to other tissues. N3 ipsilateral internal breast lymph nodes are metastatic, ipsilateral subclavian and supraclavicular lymph nodes are metastatic. Distant metastasis (M) staging: Mx with or without distant metastasis is unknown. m0 without distant metastasis. m1 with distant metastasis. II. Practical clinical staging Different clinical staging can be composed according to different TNM, which is also the most common staging used by clinicians to explain the condition to patients and their families.