Stage | T | N | M | Description |
0 | Tis | N0 | M0 | Tumor that has not grown beyond its site of origin and invaded the neighboring tissue. It includes the DCIS and LCIS. |
IA | T1 (tumor ≤ 20 mm) | N0 | M0 | Tumor which is not “in situ” but it is ≤20 mm in greater dimension. |
IB | T0 or T1 | N1mi (micro metastases) | M0 | Tumor ≤ 20 mm in greater dimension with nodal micrometastasis (greater than 0.2 mm and/or more than 200 cells, but none greater than 2 mm). |
IIA | T0 or T1 T2 (20 mm < tumor ≤ 50 mm) | N1 (metastases in 1 - 3 ipsilateral ALN(s) N0 | M0 M0 | Tumor ≤ 20 mm in greater dimension with involvement of axillary lymph nodes or tumour from 20 to 50mm without involvement of any ALNs. |
IIB | T2 T3 (tumor > 50 mm | N1 N0 | M0 M0 | Tumor from 20 to 50 mm with involvement of ALNs or tumor > 50 mm without involvement of any ALNs. |
IIIA | T0, T1 or T2 T3 | N2 (metastases in 4 - 9 ipsilateral ALNs) N1 or N2 | M0 M0 | Tumor > 50 mm with spread to ALNs, or tumor of any size with metastases in ALNs which are knitted to each other or with the surrounding tissue. |
IIIB | T4 (tumor of any size with direct extension to the chest wall and/or to the skin | N0, N1, N2 | M0 | Tumor of any size with metastases into the skin, chest wall or internal LNs of the mammary gland. |
IIIC | Any T | N3 (metastases in ≥10 ALNs, or in infra-clavicular LNs or ipsilateral internal mammary LNs) | M0 | Tumor of any size with a more widespread metastases and involvement of more LNs. |
IV | Any T | Any N | M1 (distant organs’ metastases) | Any tumor spreads to parts of the body that relocated far removed from the chest (bones, lungs, liver or distant LNs). |