Primary invasive breast cancer

American Joint Committee on Cancer (AJCC) TNM staging system (8th edition)[1]Amin MB, Edge S, Greene, F, et al, eds. AJCC cancer staging manual. 8th ed. New York: Springer; 2017.

The AJCC staging system describes the extent of disease based on the following anatomic factors: size and extent of the primary tumor (T); regional lymph node involvement (N) (assessed clinically [cN] and pathologically [pN]); and presence or absence of distant metastases (M). Nonanatomic prognostic factors (e.g., tumor grade, biomarkers [hormone-receptor status and HER2 status]) can be used to supplement staging.