| Primarytumour (T) | |
| TX | Primary tumour cannot be assessed |
| T0 | No evidence of primary tumour |
| Tis | Carcinoma in situ |
| Tis (DCIS) | Ductalcarcinoma in situ |
| Tis (LCIS) | Lobularcarcinoma in situ |
| Tis (Paget’s) | Paget’s disease (Paget disease) of the nipple NOT associated with invasive carcinoma and/or carcinoma in situ (DCIS and/or LCIS) in the underlying breast parenchyma. Carcinomas in the breast parenchyma associated with Paget’s disease are categorised based on the size and characteristics of the parenchymal disease, although the presence of Paget’s disease should still be noted. |
| T1 | Tumour ≤ 20 mm in greatest dimension |
| T1mi | Tumour ≤ 1 mm in greatest dimension |
| T1a | Tumour > 1 mm but ≤5 mm in greatest dimension |
| T1b | Tumour > 5 mm but ≤10 mm in greatest dimension |
| T1c | Tumour > 10 mm but ≤20 mm in greatest dimension |
| T2 | Tumour > 20 mm but ≤50 mm in greatest dimension |
| T3 | Tumour > 50 mm in greatest dimension |
| T4 | Tumour of any size with direct extension to the chest wall and/or to the skin (ulceration or skin nodules)e |
| T4a | Extension to the chest wall, not including only pectoralis muscle adherence/invasion |
| T4b | Ulceration and/or ipsilateral satellite nodules and/or oedema (including peaud’orange) of the skin, which do not meet the criteria for inflammatory carcinoma |
| T4c | Both T4a and T4b |
| T4d | Inflammatorycarcinomaf |
| Regionallymphnodes (N) | |
| NX | Regional lymph nodes cannot be assessed (e.g. previously removed) |
| N0 | No regional lymph node metastases |
| N1 | Metastases to movable ipsilateral level I, II axillary lymph node(s) |
| N2 | Metastases in ipsilateral level I, II axillary lymph nodes that are clinically fixed or matted; or in clinically detectedk ipsilateral internal mammary nodes in the absence of clinically evident axillary lymph node metastases |
| N2a | Metastases in ipsilateral level I, II axillary lymph nodes fixed to one another (matted) or to other structures |
| N2b | Metastases only in clinically detectedk ipsilateral internal mammary nodes and in the absence of clinically evident level I, II axillary lymph node metastases |
| N3 | Metastases in ipsilateral infraclavicular (level III axillary) lymph node(s) with or without level I, II axillary lymph node involvement; or in clinically detectedk ipsilateral internal mammary lymph node(s) with clinically evident level I, II axillary lymph node metastases; or metastases in ipsilateral supraclavicular lymph node(s) with or without axillary or internal mammary lymph node involvement |
| N3a | Metastases in ipsilateral infraclavicular lymph node(s) |
| N3b | Metastases in ipsilateral internal mammary lymph node(s) and axillary lymph node(s) |
| N3c | Metastases in ipsilateral supraclavicular lymph node(s) |
| Distant metastasis (M) | |
| 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 > 0.2 mm |