Table 1.
Breast cancer staging
| Stage | T | N | M | Description |
|---|---|---|---|---|
| 0 | Tis | N0 | M0 | Tumour that has not grown beyond its site of origin and invaded the neighbouring tissue. It includes the DCIS and LCIS. |
| IA | T1 (tumour ≤ 20 mm) | N0 | M0 | Tumour which is not ‘in situ’ but it is ≤ 20 mm in greater dimension |
| IB | T0 or T1 | N1mi (micrometastases) | M0 | Tumour ≤ 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 | N1 (metastases in 1–3 ipsilateral ALN(s) | M0 | Tumour ≤ 20 mm in greater dimension with involvement of axillary lymph nodes or tumour from 20 to 50 mm without involvement of any ALNs |
| T2 (20 mm < tumour ≤ 50 mm) | N0 | M0 | ||
| IIB | T2 | N1 | M0 | Tumour from 20 to 50 mm with involvement of ALNs or tumour > 50 mm without involvement of any ALNs |
| T3 (tumour > 50 mm | N0 | M0 | ||
| IIIA | T0, T1 or T2 | N2 (metastases in 4–9 ipsilateral ALNs) | M0 | Tumour > 50 mm with spread to ALNs, or tumour of any size with metastases in ALNs which are knitted to each other or with the surrounding tissue |
| T3 | N1 or N2 | M0 | ||
| IIIB | T4 (tumour of any size with direct extension to the chest wall and/or to the skin | N0, N1, N2 | M0 | Tumour 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 | Tumour of any size with a more widespread metastases and involvement of more LNs |
| IV | Any T | Any N | M1 (distant organs’ metastases) | Any tumour spreads to parts of the body that re located far removed from the chest (bones, lungs, liver or distant LNs) |
ALN axillary lymph node, DCIS ductal carcinoma in situ, LCIS lobular carcinoma in situ, LN lymph node
• T2, T3 and T4 tumours with nodal micrometastases (N1mi) are staged using the N1 category
• M0 means that there are no clinical or radiographic evidence of distant metastases. It includes also M0(i+) that indicates the presence of tumour cells or deposits < 0.2 mm detected microscopically or by molecular techniques in circulating blood, bone marrow or other nonregional nodal tissue in a patient without clinical and radiographic evidence of distant metastases
• Stage 3a is broadly known as a local spread of breast cancer
• T4 does not include the invasion of dermis alone
• If a patient presents with M1 disease prior to neoadjuvant systemic therapy, the stage is considered stage IV and remains stage IV regardless of response to neoadjuvant therapy
• Stage designation may be changed if postsurgical imaging studies reveal the presence of distant metastases, provided the studies are performed within 4 months of diagnosis in the absence of disease progression, and provided the patient has not received neoadjuvant therapy