Breast Cancer Staging 

Updated: Dec 07, 2018
  • Author: Joseph A Sparano, MD; Chief Editor: Marie Catherine Lee, MD, FACS  more...
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TNM Classification for Breast Cancer

The tumor-node-metastasis (TNM)  classification for staging of breast cancer is provided below. [1, 2]

Table. TNM Classification for Breast Cancer (Open Table in a new window)

Primary tumor (T)

TX

Primary tumor cannot be assessed

T0

No evidence of primary tumor

Tis

Carcinoma in situ

Tis (DCIS)

Ductal carcinoma in situ

Tis (Paget)

Paget disease of the nipple NOT associated with invasive carcinoma and/or carcinoma in situ (DCIS) in the underlying breast parenchyma. Carcinomas in the breast parenchyma associated with Paget disease are categorized on the basis of the size and characteristics of the parenchymal disease, although the presence of Paget disease should still be noted

T1

Tumor ≤ 20 mm in greatest dimension

T1mi

Tumor ≤ 1 mm in greatest dimension

T1a

Tumor > 1 mm but ≤ 5 mm in greatest dimension (round any measurement >1.0-1.9 mm to 2 mm)

T1b

Tumor > 5 mm but ≤ 10 mm in greatest dimension

T1c

Tumor > 10 mm but ≤ 20 mm in greatest dimension

T2

Tumor > 20 mm but ≤ 50 mm in greatest dimension

T3

Tumor > 50 mm in greatest dimension

T4

Tumor of any size with direct extension to the chest wall and/or to the skin (ulceration or skin nodules), not including invasion of dermis alone

T4a

Extension to chest wall, not including only pectoralis muscle adherence/invasion

T4b

Ulceration and/or ipsilateral satellite nodules and/or edema (including peau d’orange) of the skin, which do not meet the criteria for inflammatory carcinoma

T4c

Both T4a and T4b

T4d

Inflammatory carcinoma

Regional lymph nodes (N)

Clinical

cNX

Regional lymph nodes cannot be assessed (eg, previously removed)

cN0

No regional lymph node metastasis (on imaging or clinical examination)

cN1

Metastasis to movable ipsilateral level I, II axillary lymph node(s)

cN1mi

Micrometastases (approximately 200 cells, larger than 0.2 mm, but none larger than 2.0 mm)

cN2

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

cN2a

Metastases in ipsilateral level I, II axillary lymph nodes fixed to one another (matted) or to other structures

cN2b

Metastases only in ipsilateral internal mammary nodes and in the absence of axillary lymph node metastases

cN3

Metastases in ipsilateral infraclavicular (level III axillary) lymph node(s), with or without level I, II axillary node involvement, or in ipsilateral internal mammary lymph node(s) with level I, II axillary lymph node metastasis; or metastases in ipsilateral supraclavicular lymph node(s), with or without axillary or internal mammary lymph node involvement

cN3a

Metastasis in ipsilateral infraclavicular lymph node(s)

cN3b

Metastasis in ipsilateral internal mammary lymph node(s) and axillary lymph node(s)

cN3c

Metastasis in ipsilateral supraclavicular lymph node(s)

Note: (sn) and (f) suffixes should be added to the N category to denote confirmation of metastasis by sentinel node biopsy or fine needle aspiration/core needle biopsy, respectively.

Pathologic (pN)

pNX

Regional lymph nodes cannot be assessed (for example, previously removed, or not removed for pathologic study)

pN0

No regional lymph node metastasis identified histologically, or isolated tumor cell clusters (ITCs) only. Note: ITCs are defined as small clusters of cells ≤ 0.2 mm, or single tumor cells, or a cluster of < 200 cells in a single histologic cross-section; ITCs may be detected by routine histology or by immunohistochemical (IHC) methods; nodes containing only ITCs are excluded from the total positive node count for purposes of N classification but should be included in the total number of nodes evaluated

pN0(i)

No regional lymph node metastases histologically, negative IHC

pN0(i+)

ITCs only in regional lymph node(s)

pN0(mol-)

No regional lymph node metastases histologically, negative molecular findings (reverse transcriptase polymerase chain reaction [RT-PCR])

pN0(mol+)

Positive molecular findings by RT-PCR; no ITCs detected 

pN1

Micrometastases; or metastases in 1-3 axillary lymph nodes and/or in internal mammary nodes; and/or in clinically negative internal mammary nodes with micrometastases or macrometastases by sentinel lymph node biopsy

pN1mi

Micrometastases (200 cells, > 0.2 mm but none > 2.0 mm)

pN1a

Metastases in 1-3 axillary lymph nodes (at least 1 metastasis > 2.0 mm)

pN1b

Metastases in ipsilateral internal mammary lymph nodes, excluding ITCs, detected by sentinel lymph node biopsy

pN1c

Metastases in 1-3 axillary lymph nodes and in internal mammary sentinel nodes (ie, pN1a and pN1b combined)

pN2

Metastases in 4-9 axillary lymph nodes; or positive ipsilateral internal mammary lymph nodes by imaging in the absence of axillary lymph node metastases

pN2a

Metastases in 4-9 axillary lymph nodes (at least 1 tumor deposit > 2.0 mm)

pN2b

Clinically detected* metastases in internal mammary lymph nodes with or without microscopic confirmation; with pathologically negative axillary lymph nodes

pN3

Metastases in ≥ 10 axillary lymph nodes; or in infraclavicular (level III axillary) lymph nodes; or positive ipsilateral internal mammary lymph nodes by imaging in the presence of one or more positive level I, II axillary lymph nodes; or in > 3 axillary lymph nodes and micrometastases or macrometastases by sentinel lymph node biopsy in clinically negative ipsilateral internal mammary lymph nodes; or in ipsilateral supraclavicular lymph nodes 

pN3a

Metastases in ≥ 10 axillary lymph nodes (at least 1 tumor deposit > 2.0 mm); or metastases to the infraclavicular (level III axillary lymph) nodes

pN3b

pN1a or pN2a in the presence of cN2b (positive internal mammary nodes by imaging) or pN2a in the presence of pN1b

pN3c

Metastases in ipsilateral supraclavicular lymph nodes

*"Clinically detected" is defined as detected by imaging studies (excluding lymphoscintigraphy) or by clinical examination and having characteristics highly suspicious for malignancy or a presumed pathologic macrometastasis on the basis of FNA biopsy with cytologic examination.

Distant metastasis (M)

M0

No clinical or radiographic evidence of distant metastasis

cM0(i+)

No clinical or radiographic evidence of distant metastases in the presence of tumor cells or deposits no larger than 0.2 mm detected microscopically or by molecular techniques in circulating blood, bone marrow, or other nonregional nodal tissue in a patient without symptoms or signs of metastase

cM1

Distant metastases detected by clinical and radiographic means 

pM1

Any histologically proven metastases in distant organs; or if in non-regional nodes, metastases > 0.2 mm 

Table. Histologic grade (Open Table in a new window)

Histologic grade (G)

GX

Grade cannot be assessed

G1

Low combined histologic grade (favorable)

G2

Intermediate combined histologic grade (moderately favorable)

G3

High combined histologic grade (unfavorable)

Table. Anatomic stage/prognostic groups (Open Table in a new window)

Stage

T

N

M

0

Tis

N0

M0

IA

T1

N0

M0

IB

T0

N1mi

M0

 

T1

N1mi

M0

IIA

T0

N1

M0

 

T1

N1

M0

 

T2

N0

M0

IIB

T2

N1

M0

 

T3

N0

M0

IIIA

T0

N2

M0

 

T1

N2

M0

 

T2

N2

M0

 

T3

N1

M0

 

T3

N2

M0

IIIB

T4

N0

M0

 

T4

N1

M0

 

T4

N2

M0

IIIC

Any T

N3

M0

IV

Any T

Any N

M1

Notes:

  • T1 includes T1mi.
  • T0 and T1 tumors with nodal micrometastases (N1mi) are staged as Stage IB.
  • T2, T3, and T4 tumors with nodal micrometastases (N1mi) are staged using the N1 category.
  • M0 includes M0(i+)
  • The designation pM0 is not valid; any M0 is clinical.
  • 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.
  • Staging following neoadjuvant therapy is designated with “yc” or “yp” prefix to the T and N classification. No anatomic stage group is assigned if there is a complete pathologic response (pCR) to neoadjuvant therapy, for example, ypT0ypN0cM0.