Table 1: details of the TNM staging system

T categories for breast cancer

 

TX: 

Primary tumor cannot be assessed.

T0: 

No evidence of primary tumor.

T1: 

Tumor is 2 cm or less across.

T2: 

Tumor is more than 2 cm but not more than 5 cm across.

T3: 

Tumor is more than 5 cm across.

T4: 

Tumor of any size growing into the chest wall or skin. This includes inflammatory breast cancer.

N categories for breast cancer

 

NX: 

Nearby lymph nodes cannot be assessed (for example, if they were removed previously).

N0: 

Cancer has not spread to nearby lymph nodes.

N1: 

Metastases to movable ipsilateral axillary lymph node(s)

N2: 

Metastases in ipsilateral axillary lymph nodes that are clinically fixed or matted; or in clinically detected ipsilateral internal mammary nodes in the absence of clinically evident axillary lymph node metastases

N3: 

 

Metastases in ipsilateral infraclavicular lymph node(s) with or without axillary lymph node involvement; or in clinically detected  ipsilateral internal mammary lymph node(s) with clinically evident axillary lymph node metastases; or metastases in ipsilateral supraclavicular lymph node(s) with or without axillary or internal mammary lymph node involvement

M categories for breast cancer

 

M0: 

No clinical or radiographic evidence of distant metastases

M1:

Distant detectable metastases as determined by classic clinical and radiographic means and/or histologically proven larger than 0.2 mm