Table 40.2 Continued pNX Regional lymph nodes cannot be assessed (e.g., previously removed or not removed for pathologic study) pN0 No regional lymph node metastasis identified histologically pN0(i−) No regional lymph node metastases histologically, negative IHC pN0(i+) Malignant cells in regional lymph node(s) no greater than 0.2 mm (detected by H&E or IHC including ITC) pN0(mol−) No regional lymph node metastases histologically, negative molecular findings (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 to 3 axillary lymph nodes; and/or in internal mammary nodes with metastases detected by sentinel lymph node biopsy but not clinically detected pN1mi Micrometastasis (>0.2 mm and/or more than 200 cells, but none >2.0 mm) pN1a Metastases in 1 to 3 axillary lymph nodes, at least one metastasis >2.0 mm pN1b Metastases in internal mammary nodes with micrometastases or macrometastases detected by sentinel lymph node biopsy but not clinically apparent pN1c Metastases in 1 to 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 to 9 axillary lymph nodes; or in clinically detected internal mammary lymph nodes in the absence of axillary lymph node metastases pN2a Metastases in 4 to 9 axillary lymph nodes (at least one 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 ten or more axillary lymph nodes; or in infraclavicular (level III axillary) lymph nodes; or in clinically detected ipsilateral internal mammary lymph nodes in the presence of one or more positive level I, II axillary lymph nodes; or in more than three 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 ten or more axillary lymph nodes (at least one tumor deposit greater than 2.0 mm); or metastasis to the infraclavicular (level III axillary lymph) nodes pN3b Metastases in clinically detected ipsilateral internal mammary nodes in the presence of one or more positive axillary lymph nodes; or in more than three axillary lymph nodes and in internal mammary lymph nodes with micrometastases or macrometastases detected by sentinel lymph node biopsy but not clinically detected
M0 No clinical or radiologic 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 larger than 0.2 mm
From Edge SB, Byrd DB, Compton CC, et al., eds. Breast. In AJCC cancer staging manual. 7th ed. New York: Springer, 2010:419–460, with permission.