Radiation Oncology/Breast/Staging

Current staging

AJCC 7th Edition (2009)
Primary Tumor:

• T0 - no primary tumor found
• Tis - in situ (DCIS or LCIS or Paget's)
• T1 ≤ 2 cm
  • T1mi ≤ 0.1 cm (microinvasive)
  • T1a > 0.1 to 0.5 cm
  • T1b > 0.5 to 1 cm
  • T1c > 1 to 2 cm
• T2 > 2 to 5 cm
• T3 > 5 cm
• T4 Chest wall /skin
  • T4a Chest wall (not including pectoralis muscle)
  • T4b Skin edema (peau d'orange), ulceration, or satellite skin nodules
  • T4c Both 4a and 4b
  • T4d Inflammatory carcinoma

Regional Lymph Nodes

Clinical staging		Pathologic staging
cN0	No lymph node metastases	pN0	No lymph node metastases
cN1	Movable ipsilateral axillary lymph nodes	pN1mi	Micrometastases (> 0.2mm and/or more than 200 cells, but <= 2.0 mm)
		pN1a	1-3 axillary lymph nodes (at least 1 > 2.0mm)
		pN1b	Metastases in IM nodes (micrometastases, or macrometastases detected by SLN biopsy but not clinically detected)
		pN1c	1-3 axillary lymph nodes and metastases in IM nodes (micrometastases, or macromets detected by SLN but not clinically detected)
cN2a	Ipsilateral axillary lymph nodes fixed or matted	pN2a	4-9 axillary lymph nodes (at least 1 > 2.0 mm)
cN2b	Clinically detected internal mammary nodes in the absence of axillary lymph node metastases	pN2b	Metastases in clinically detected IM nodes in the absence of axillary lymph nodes
cN3a	Infraclavicular lymph nodes (level III)	pN3a	10 or more axillary lymph nodes (at least 1 > 2.0 mm); or infraclavicular (level III) lymph nodes
cN3b	Clinically apparent internal mammary nodes with axillary lymph node involvement	pN3b	Metastases in clinically detected IM nodes in the presence of positive axillary nodes; or microscopic IM nodes and more than 3 axillary lymph nodes
cN3c	Supraclavicular lymph nodes	pN3c	Supraclavicular lymph nodes

Mnemonics: "A" Nodes are "A"xillary, "B" Nodes are internal "B"reast (eg IMNs), "C" Nodes are supra"C"lavicular - excludes N1 subgroups

Note: For node counting, at least 1 LN must contain a tumor deposit > 2mm and all remaining quantified nodes must contain tumor deposits > 0.2 mm (at least micromets). Nodes containing only tumor deposits <= 0.2mm (ITCs) are excluded from the positive node count (but should be recorded as additional ITC involved nodes)

Distant Metastases:

• M0 - none
• cM0(i+) - no clinical or radiographic evidence of distant metastases, but tumor cells detected in circulating blood, bone marrow, or other tissues (e.g. prophylactically removed ovaries), ≤ 0.2 mm, in a patient without symptoms or signs of metastases.
• M1 - distant detectable metastases; or histologically proven > 0.2 mm

Stage Grouping:

• 0: Tis
• IA: T1 N0
• IB: T0-T1 N1mi
• IIA: T0-1 N1 or T2 N0
• IIB: T2 N1 or T3 N0
• IIIA: T3 N1 or T0-3 N2
• IIIB: T4 N0-2
• IIIC: N3
• IV: M1

Changes from 6th edition:

• T1mic changed to T1mi to indicate microscopic disease
• Clarification of wording of "not clinically detected" and "clinically detected" internal mammary nodes. *Clarification of Isolated tumor cells (ITC).
• Subdivision of Stage I into IA and IB (IB includes T0-T1 with N1mi nodal micrometastases). Otherwise, no changes in TNM or Overall Stage
• New cM0(i+) category for circulating tumor cells or incidentally discovered metastatic cells in other tissue
• Clarification of assigning staging after neoadjuvant therapy (yc or ypTNM)

8th Edition

AJCC 8th edition (2017)

• To be used for staging beginning Jan 1, 2018.
• The prognostic stage group is preferred for patient care, is to be used for reporting of all cancer patients. The anatomic stage group is provided so that stage can be assigned when biomarkers cannot be routinely obtained.
• LCIS is no longer included as in situ

Primary Tumor:

• T0 - no primary tumor found
• Tis (DCIS)
  • Note: LCIS is no longer included (benign)
• Tis (Paget)
• T1 ≤ 2 cm
  • T1mi ≤ 0.1 cm (microinvasive)
  • T1a > 0.1 but ≤ 0.5 cm (round any measurement from >1.0-1.9 mm to 2 mm)
  • T1b > 0.5 but ≤ 1 cm
  • T1c > 1 but ≤ 2 cm
• T2 > 2 but ≤ 5 cm
• T3 > 5 cm
• T4 Chest wall /skin
  • T4a Chest wall (not including pectoralis muscle)
  • T4b Skin edema (peau d'orange), ulceration, or satellite skin nodules
    (satellite tumor nodules in the skin must be evident grossly. Those identified only microscopically do not constitute T4b)
  • T4c Both 4a and 4b
  • T4d Inflammatory carcinoma

Regional Lymph Nodes

Clinical staging		Pathologic staging
cN0	No lymph node metastases	pN0	No lymph node metastases
		pN0(i+)	ITCs only (malignant cell clusters no larger than 0.2 mm) in regional lymph nodes
		pN0(mol+)	Positive molecular findings by RT-PCR; no ITCs detected
cN1	Metastases to movable ipsilateral level I and II axillary lymph node(s)	pN1mi	Micrometastases (approx 200 cells, larger than 0.2 mm, but none larger than 2.0 mm)
cN1mi	Micrometastases (approx 200 cells, larger than 0.2 mm, but none larger than 2.0 mm)	pN1a	Met to 1-3 axillary lymph nodes (at least 1 > 2.0mm)
		pN1b	Met to ipsilateral internal mammary sentinel LNs (excluding ITCs)
		pN1c	pN1a and pN1b combined
cN2a	Met in ipsilateral level I and II axillary lymph nodes fixed to one another (matted) or to other structures	pN2a	Met to 4-9 axillary lymph nodes (at least 1 > 2.0 mm)
cN2b	Met only in ipsilateral internal mammary LNs in the absence of axillary LN mets	pN2b	Met in clinically detected IM nodes (with/without microscopic confirmation) with pathologically negative axillary lymph nodes
cN3a	Met in ipsilateral infraclavicular lymph nodes (level III)	pN3a	Met in 10 or more axillary lymph nodes (at least 1 > 2.0 mm); or met to infraclavicular (level III) lymph nodes
cN3b	Met in ipsilateral internal mammary LNs and axillary LNs	pN3b	pN1a or pN2a in the presence of positive internal mammary LNs by imaging; or pN2a in the presence of pN1b (IM sentinel LN)
cN3c	Supraclavicular lymph nodes	pN3c	Supraclavicular lymph nodes
For cN, use (sn) suffix to denote confirmation of metastases by sentinel LN biopsy; use (f) suffix to denote confirmation by FNA or core needle biopsy. cN1mi for pts who undergo SLN biopsy before tumor resection (i.e. neoadjuvant therapy)		For pN, use (sn) and (f) suffixes if confirmed by SLN biopsy or FNA/core biopsy with no further resection of LNs

Distant Metastases:

• M0 - none
• cM0(i+) - no clinical or radiographic evidence of distant metastases, but tumor cells detected in circulating blood, bone marrow, or other tissues (e.g. prophylactically removed ovaries), ≤ 0.2 mm, in a patient without symptoms or signs of metastases.
• M1 - distant detectable metastases; or histologically proven met > 0.2 mm (pM1)

Prognostic Stage Grouping:

Anatomic Stage Grouping:

• 0: Tis
• IA: T1 N0
• IB: T0-T1 N1mi
• IIA: T0-1 N1 or T2 N0
• IIB: T2 N1 or T3 N0
• IIIA: T3 N1 or T1-3 N2
• IIIB: T4 N0-2
• IIIC: N3
• IV: M1

Source: [1]

Older staging versions

AJCC 6th edition (2002)
Primary Tumor:

• T0 - no primary tumor found
• Tis - in situ (DCIS or LCIS or Paget's)
• T1 ≤ 2 cm
  • T1mic ≤ 0.1 cm (microinvasive)
  • T1a > 0.1 to 0.5 cm
  • T1b > 0.5 to 1 cm
  • T1c > 1 to 2 cm
• T2 > 2 to 5 cm
• T3 > 5 cm
• T4 Chest wall /skin
  • T4a Chest wall (not including pectoralis muscle)
  • T4b Skin edema (peau d'orange), ulceration, or satellite skin nodules
  • T4c Both 4a and 4b
  • T4d Inflammatory carcinoma

Lymph nodes

Clinical staging		Pathologic staging
cN0	No lymph node metastases	pN0	No lymph node metastases
cN1	Movable ipsilateral axillary lymph nodes	pN1mi	Micrometastases (> 0.2mm but <= 2.0 mm)
		pN1a	1-3 axillary lymph nodes
		pN1b	Microscopic involvement of IM nodes (not clinically apparent) but no axillary nodes
		pN1c	1-3 axillary lymph nodes and microscopic involvement of IM nodes
cN2a	Ipsilateral axillary lymph nodes fixed or matted	pN2a	4-9 axillary lymph nodes
cN2b	Clinically apparent internal mammary nodes in the absence of axillary lymph node metastases	pN2b	Clinically apparent IM nodes in the absence of axillary lymph nodes
cN3a	Infraclavicular lymph nodes	pN3a	10 or more axillary lymph nodes; or infraclavicular lymph nodes
cN3b	Clinically apparent internal mammary nodes with axillary lymph node involvement	pN3b	Clinically apparent IM nodes in the presence of positive axillary nodes; or microscopic IM nodes and more than 3 axillary lymph nodes
cN3c	Supraclavicular lymph nodes	pN3c	Supraclavicular lymph nodes

Mnemonics: "A" Nodes are "A"xillary, "B" Nodes are internal "B"reast (eg IMNs), "C" Nodes are supra"C"lavicular - excludes N1 subgroups

Nodes:

• Isolated tumor cells (ITC) - small clusters of cells <= 0.2 mm (and < 200 cells), usually with no histologic evidence of malignant activity (such as proliferation or stromal reaction). Designated pN0. If IHC or PCR is performed, may be designated pN0(i+),pN0(i-),pN0(mol+),or pN0(mol-).
• Micrometastases (pN1mi) - > 0.2mm but <= 2.0 mm. May also be designated pN1mi(i+) or pN1mi(i-) if IHC is performed.

Distant metastasis:

• M0 No
• M1 Yes

Stage grouping:

• Stage 0: Tis
• Stage I: T1,N0,M0
• Stage IIA: T0-1,N1,M0 or T2,N0,M0
• Stage IIB: T2,N1,M0 or T3,N0,M0
• Stage IIIA: T3,N1,M0 or T0-3,N2,M0
• Stage IIIB: T4,any N,M0
• Stage IIIC: any T,N3,M0
• Stage IV: any T,any N,M1

AJCC 5th Edition (1997)

• pN1a - micrometastases (<0.2 cm)
• pN1bi - 1-3 nodes, < 2 cm
• pN1bii - 4+ nodes, < 2 cm
• pN1biii - extracapsular extension, < 2 cm
• pN1biv - > 2 cm

Otherwise unchanged compared to 6th edition

New Classifications

For additional information, see Tissue microarrays (Breast/Breast overview)

Gene expression profiling is the basis for additional classification schemes.

• Luminal A type - ER+ and/or PR+, HER2–. Usually low grade. These express genes similar to normal cells lining breast ducts and glands
• Luminal B type - ER+ and/or PR+, HER2+. These are similar to luminal A, but grow faster and have a slightly poorer prognosis.
• Basal type - ER–, PR–, HER2–, cytokeratin 5/6 positive, and/or HER1+. Also known as "triple negative". Higher prevalence in young African American women.
• HER2 type - ER-, PR-, HER2+. Usually high histological grade.