for breast tumors, bigger than 2cm changes the t category. N refers to node status, which changes as the tumor spreads into lymph nodes. M refers to metastasis, which indicates that the cancer has spread to places beyond the breast. The tnm classifications were developed by the american joint committee on cancer. The staging system most often used for breast cancer is the american joint committee on cancer (ajcc) tnm system. The most recent ajcc system, effective january 2018, has both clinical and pathologic staging systems for breast cancer the pathologic stage (also called the surgical stage) is determined by examining tissue removed during an. The tnm system, the grading system, and the biomarker status are combined to find out the breast cancer stage. The tnm system is used to describe the size of the primary tumor and the spread of cancer to nearby lymph nodes or other parts of the body. Clinical tnm staging for breast cancer is done by physical examination of the patient and loboratory and radiology investigations (discussed below). It is called as t1 when the tumor size is less than or equal to 2 cm. Breast cancer (clinical) tnm staging ctnm staging ajcc 2017 breast cancer (pathological) tnm staging ptnm staging ajcc 2017. Summary clinical recommendation - summary clinical recommendation - complete (cmaj) link. Breast cancer staging refers to tnm classification of breast carcinomas. The system applies to epithelial malignancies and does not apply to breast sarcomas, phyllodes tumor, or breast lymphomas. The following article reflects the 8 th edition manual published by the american joint committee on cancer (ajcc), which has been used for staging since january 1, 2018 2. Tnm was adopted by the union for international cancer control (uicc) in the 1950s. Tnm was adopted by the american joint committee on cancer (ajcc) and issued their first edition in1977. Although there were refinements, breast cancer staging remained substantially the same over 60 years.