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Breast Cancer Treatment (PDQ®)

  • Updated: 09/25/2014

Table 3. Regional Lymph Nodes (N)a

Clinical  
NXRegional lymph nodes cannot be assessed (e.g., previously removed).
N0No regional lymph node metastases.
N1Metastases to movable ipsilateral level I, II axillary lymph node(s).
N2Metastases in ipsilateral level I, II axillary lymph nodes that are clinically fixed or matted.
OR
Metastases in clinically detectedb ipsilateral internal mammary nodes in the absence of clinically evident axillary lymph node metastases.
N2aMetastases in ipsilateral level I, II axillary lymph nodes fixed to one another (matted) or to other structures.
N2bMetastases only in clinically detectedb ipsilateral internal mammary nodes and in the absence of clinically evident level I, II axillary lymph node metastases.
N3Metastases in ipsilateral infraclavicular (level III axillary) lymph node(s) with or without level I, II axillary lymph node involvement.
OR
Metastases in clinically detectedb ipsilateral internal mammary lymph node(s) with clinically evident level I, II axillary lymph node metastases.
OR
Metastases in ipsilateral supraclavicular lymph node(s) with or without axillary or internal mammary lymph node involvement.
N3aMetastases in ipsilateral infraclavicular lymph node(s).
N3bMetastases in ipsilateral internal mammary lymph node(s) and axillary lymph node(s).
N3cMetastases in ipsilateral supraclavicular lymph node(s).

aReprinted with permission from AJCC: Breast. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 347-76.
b 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 based on fine-needle aspiration biopsy with cytologic examination. Confirmation of clinically detected metastatic disease by fine-needle aspiration without excision biopsy is designated with an (f) suffix, for example, cN3a(f). Excisional biopsy of a lymph node or biopsy of a sentinel node, in the absence of assignment of a pT, is classified as a clinical N, for example, cN1. Information regarding the confirmation of the nodal status will be designated in site-specific factors as clinical, fine-needle aspiration, core biopsy, or sentinel lymph node biopsy. Pathologic classification (pN) is used for excision or sentinel lymph node biopsy only in conjunction with a pathologic T assignment.