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 &le; 2 cm
 * T1mi &le; 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

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), &le; 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 &le; 2 cm
 * T1mi &le; 0.1 cm (microinvasive)
 * T1a > 0.1 but &le; 0.5 cm (round any measurement from >1.0-1.9 mm to 2 mm)
 * T1b > 0.5 but &le; 1 cm
 * T1c > 1 but &le; 2 cm
 * T2 > 2 but &le; 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

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), &le; 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:

Older staging versions
AJCC 6th edition (2002) Primary Tumor:
 * T0 - no primary tumor found
 * Tis - in situ (DCIS or LCIS or Paget's)
 * T1 &le; 2 cm
 * T1mic &le; 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

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) Otherwise unchanged compared to 6th edition
 * pN1a - micrometastases (<0.2 cm)
 * pN1bi - 1-3 nodes, < 2 cm
 * pN1bii - 4+ nodes, < 2 cm
 * pN1biii - extracapsular extension, < 2 cm
 * pN1biv - > 2 cm

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.