Breast Cancer Staging 

Updated: Dec 05, 2016
  • Author: Joseph A Sparano, MD, MD; Chief Editor: Marie Catherine Lee, MD, FACS  more...
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TNM Classification for Breast Cancer

The TNM classification for staging of breast cancer is provided below. [1]

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 (LCIS) Lobular carcinoma in situ
Tis (Paget) 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 disease are categorized based on 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
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)
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
NX Regional lymph nodes cannot be assessed (eg, previously removed)
N0 No regional lymph node metastasis
N1 Metastasis 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 detected* ipsilateral internal mammary nodes in the absence of clinically evident axillary lymph node metastasis
N2a Metastases in ipsilateral level I, II axillary lymph nodes fixed to one another (matted) or to other structures
N2b Metastases only in clinically detected* 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 node involvement, or in clinically detected * ipsilateral internal mammary lymph node(s) and in the presence of clinically evident level I, II axillary lymph node metastasis; or metastasis in ipsilateral supraclavicular lymph node(s), with or without axillary or internal mammary lymph node involvement
N3a Metastasis in ipsilateral infraclavicular lymph node(s)
N3b Metastasis in ipsilateral internal mammary lymph node(s) and axillary lymph node(s)
N3c Metastasis in ipsilateral supraclavicular lymph node(s)
*"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 fine-needle aspiration (FNA) biopsy with cytologic examination.
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. Note: Isolated tumor cell clusters (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+) Malignant cells in regional lymph node(s) ≤ 0.2 mm (detected by hematoxylin-eosin [H&E] stain or IHC, including ITC)
pN0(mol-) No regional lymph node metastases histologically, negative molecular findings (reverse transcriptase polymerase chain reaction [RT-PCR])
pN0(mol+) Positive molecular findings (RT-PCR) but no regional lymph node metastases detected by histology or IHC
pN1 Micrometastases; or metastases in 1-3 axillary lymph nodes and/or in internal mammary nodes, with metastases detected by sentinel lymph node biopsy but not clinically detected†
pN1mi Micrometastases (> 0.2 mm and/or > 200 cells, but none > 2.0 mm)
pN1a Metastases in 1-3 axillary lymph nodes (at least 1 metastasis > 2.0 mm)
pN1b Metastases in internal mammary nodes, with micrometastases or macrometastases detected by sentinel lymph node biopsy but not clinically detected†
pN1c Metastases in 1-3 axillary lymph nodes and in internal mammary lymph nodes, with micrometastases or macrometastases detected by sentinel lymph node biopsy but not clinically detected†
pN2 Metastases in 4-9 axillary lymph nodes or in clinically detected‡ internal mammary lymph nodes 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 Metastases in clinically detected‡ internal mammary lymph nodes in the absence of axillary lymph node metastases
pN3 Metastases in ≥ 10 axillary lymph nodes; or in infraclavicular (level III axillary) lymph nodes; or in clinically detected‡ ipsilateral internal mammary lymph nodes in the presence of ≥ 1 positive level I, II axillary lymph nodes; or in > 3 axillary lymph nodes and in internal mammary lymph nodes, with micrometastases or macrometastases detected by sentinel lymph node biopsy but not clinically detected†; 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 Metastases in clinically detected‡ ipsilateral internal mammary lymph nodes in the presence of ≥ 1 positive axillary lymph nodes; or in > 3 axillary lymph nodes and in internal mammary lymph nodes, with micrometastases or macrometastases detected by sentinel lymph node biopsy but not clinically detected†
pN3c Metastases in ipsilateral supraclavicular lymph nodes
*Classification is based on axillary lymph node dissection, with or without sentinel lymph node biopsy. Classification based solely on sentinel lymph node biopsy without subsequent axillary lymph node dissection is designated (sn) for "sentinel node"—for example, pN0(sn).



† "Not clinically detected" is defined as not detected by imaging studies (excluding lymphoscintigraphy) or not detected by clinical examination.



‡ "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, but deposits of molecularly or microscopically detected tumor cells in circulating blood, bone marrow, or other nonregional nodal tissue that are no larger than 0.2 mm in a patient without symptoms or signs of metastases
M1 Distant detectable metastases as determined by classic clinical and radiographic means and/or histologically proven > 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