TNM Staging
Staging is a description of the extent of disease. One type of staging is clinical: it is based on complete physical examination, imaging studies, and pathologic examination of the breast or other tissue. Another type of staging is pathologic and is based on tumor type, size, and extension. Complete staging should include all the clinical and pathologic data. Generally a higher stage corresponds to more extensive disease and graver prognosis. For staging breast cancer, the American Joint Committee on Cancer (AJCC) TNM system is most commonly used (Table 1). The letters in this staging system indicate the following (AJCC 2013):
T = tumor size
N = lymph node status
M = metastasis