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Anatomic Staging of Breast Cancer*

Stage

Tumor

Regional Lymph Node/Distant Metastasis†

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

TI‡

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

* Adapted from: Hortobagyi GN, Connolly JL, D’Orsi CJ, Edge SB, Mittendorf EA, et al: Breast. In: Amin MB, Edge S, Greene F, et al, eds; American Joint Committee on Cancer. AJCC cancer staging manual. 8th ed. New York, NY: Springer. 2017. Version 9 changes, when available, can be found on the American Joint Committee on Cancer (AJCC) site AJCC Version 9 Cancer Staging System.

† Classification of regional lymph nodes (N) is divided into clinical (cN) and pathologic (pN), which have slightly different descriptions.

‡ T1 includes T1mi.

§ Here, N1 excludes N1mi.

Tis = ductal carcinoma in situ or Paget disease of the nipple with no tumor (Paget disease with a tumor is classified by tumor size); T1 = tumor ≤ 2 cm; T1mi = tumor ≤ 0.1 cm; T2 = tumor > 2 but ≤ 5 cm; T3 = tumor > 5 cm; T4 = any size tumor with extension to chest wall and/or skin and with ulceration or skin nodules or inflammatory cancer.

NX = Nearby nodes not assessable (for example, because removed previously); N0 = no spread to nearby nodes or only isolated tumor cells; N1 = spread to 1–3 ipsilateral movable, low or midaxillary nodes and/or metastases detected by sentinel lymph node biopsy in clinically negative internal mammary lymph nodes (pN1); N1mi = N1 nodes with micrometastases (about 200 cells > 0.2 mm, but none > 2 mm); N2 = any of the following:

  • Spread to ipsilateral low or midaxillary nodes that are fixed or matted, detected by clinical examination (cN2)

  • Spread to 4–9 axillary lymph nodes, detected by testing (pN2)

  • Spread to internal mammary nodes but not axillary nodes as detected by clinical examination or imaging

N3 = any of the following:

  • Spread to ipsilateral internal mammary nodes plus axillary nodes as detected by clinical examination or imaging

  • Spread to infraclavicular nodes

  • Spread to supraclavicular nodes

  • Spread to ≥ 10 axillary lymph nodes

  • Spread to > 3 axillary lymph nodes and micrometastases or macrometastases by sentinel lymph node biopsy in clinically negative internal mammary nodes (pN3)

M0 = no distant metastases; M1 = distant metastases present.

Adapted from the American Joint Committee on Cancer, AJCC Cancer Staging Manual, Eighth Edition (2017). Springer New York, Inc.

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