pT4aN0Mx is a method of describing pathological staging, with the p prefix representing the fact that this staging is a postoperative pathological staging, that is, an indicator of the type of staging obtained after biopsy of the pathologic tissue. Where T is the initials of tumor tumor, which is the English word for tumor, refers to the primary tumor lesion, which is classified according to the size of the tumor, and its infiltration of the surrounding tissues. N is the initial letter of lymph node node, which refers to the involvement of regional lymph nodes, where N0 means no lymph node metastasis. m refers to distant metastasis, M0 means no distant metastasis; M1 means distant metastasis; Mx means that it is not possible to tell whether there is distant metastasis, and further examination is needed. Pathologic staging of pTNM is performed for almost all cancers in the clinic, and by determining the pathologic staging, the subsequent treatment plan can be guided.