Breast Cancer Staging

a. Primary Tumor Staging
o T1: <= 2.0 cm
o T1mic: Microinvasion <= 0.1 cm
o T1a: 0.1< T <=0.5 cm
o T1b: 0.5< T <= 1.0 cm
o T1c: 1.0< T <= 2.0 cm
o T2: 2.0 < T <= 5.0
o T3: 5.0 cm < T
o T4: Tumor of any size with direct extension to (a) chest wall or (b) skin
o T4a: Extension to chest wall, not including pectoralis muscle
o T4b: Edema (peau d'orange) or ulceration of the skin , or satellite skin nodules(same breast)
o T4c: Both T4a and T4b
o T4d: Inflammatory carcinoma

b. Clinical/ Radiological Regional Lymph Node Staging
o NX: cannot be assessed (e.g., previously removed)
o N0: No LN
o N1: Metastasis to movable ipsilateral axillary lymph node(s)
o N2:
o N2a: ipsilateral axillary lymph nodes fixed or matted
o N2b: ipsilateral internal mammary nodes with no axillary involvement
o N3
o N3a: ipsilateral infraclavicular
o N3b: ipsilateral internal mammary + axillary lymph node(s)
o N3B = N1/N2A + N2B
o N3c: ipsilateral supraclavicular lymph node(s)

c. PATHOLOGIC Nodal Staging
o pNX: cannot be assessed (e.g., not removed for pathologic study or previously removed)
o pN0:
• pN0(I-): No LN, negative IHC
• pN0(I+): No LN, positive IHC, BUT IHC cluster <= 0.2 mm
• pN0(mol-): No LN & negative molecular findings (RT-PCR)
• pN0(mol+): No LN & and positive molecular findings (RT-PCR)
o pN1: 1-3 axillary LN and/or internal mammary microscopic
• pN1mi: Micrometastasis (0.2 mm< N1mic < = 2.0 mm)
• pN1a: 1-3 axillary LN
• pN1b: microscopic internal mammary nodes NOT CLINICAL
• pN1c:N1A + N1B
o pN2:
• pN2a: 4-9 axillary LN(at least one tumor deposit > 2.0 mm)
• pN2b: Clinical internal mammary LN with no axillary involvement
o pN3:
• pN3a: 10 < LN (at least one tumor deposit larger than 2.0 mm); or, metastasis to the infraclavicular lymph nodes
• pN3b: Clinical and Pathologic ipsilateral internal mammary + axillary LN; or, in more than three axillary lymph nodes and in internal mammary lymph nodes with microscopic disease detected by sentinel lymph node dissection but not clinically apparente
• pN3c: Metastasis in ipsilateral supraclavicular lymph nodes
DISTANT METASTASIS (M)
MX: Presence of distant metastasis cannot be assessed
M0: No distant metastasis
M1: Distant metastasis

N0 N1 N2 N3 M1
T1 I IIA IIIA IIIC IV
T2 IIA IIB IIIA IIIC IV
T3 IIB IIIA IIIA IIIC IV
T4 IIIB IIIB IIIB IIIC IV