Imaging diagnosis of metastatic breast cancer

Pesapane, Filippo; Downey, Kate; Rotili, Anna; Cassano, Enrico; Koh, Dow-Mu

doi:10.1186/s13244-020-00885-4

Insights into Imaging

Table 1 Breast cancer staging

From: Imaging diagnosis of metastatic breast cancer

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

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