Breast cancer staging

T1 breast cancer. (WC/CRUK)

This article deals with breast cancer staging.

An introduction to cancer staging is in the cancer staging article. An introduction to breast pathology is in the breast pathology article.

T stage

Tumour:

• pT1: <= 20 mm.
  • pT1mic <= 1 mm.
  • pT1a > 1 mm and <= 5 mm.
  • pT1b > 5 mm and <= 10 mm.
  • pT1c > 10 mm and <= 20 mm.
• pT2: > 20 mm and <= 50 mm
• pT3: > 50 mm.
• pT4: chest wall or skin involvement.

Notes:

• Values should be rounded to the nearest millimetre.
  • Therefore:
    • 1.4 mm would be pT1mic.
    • 1.5 mm would be pT1a.

Images

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  T1. (WC/CRUK)

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  T2. (WC/CRUK)

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  T3. (WC/CRUK)

N stage

Sampling usually selective, i.e. sentinel lymph nodes only.

Indications for lymph node sampling

Indications:

• Extensive DCIS.
• Biopsy suspicious for invasion or with microinvasion.
• Clinical findings (large palable mass) or radiology findings (irregular features) suggestive of invasion.
• Planned mastectomy.

Definitions

Definitions:

• Isolated tumour cells: <=0.2 mm or <=200 cells -- in a single cross-section. †
• Micrometastasis: <=0.2 cm and ( >0.2 mm or >200 cells ).
• Macrometastasis: >0.2 cm.

Notes:

• † The American Cancer Society web site says "or". The CAP protocol says "and/or" and notes it is all subjective.
• Isolated tumour cells are essentially ignored if the there is at least one macrometastasis.

Details

Lymph nodes:

• pN0: nil.
  • pN0(i+): <=0.2 mm and <200 cells.
• pN1: 1-3 axillary LNs or internal mammary LNs.
  • pN1mi: <=0.2 cm and ( >0.2 mm or >=200 cells ).
  • pN1a.
  • pN1b.
  • PN1c.
• pN2 4-9 positive LNs; internal mammary LNs or axillary LNs.
• pN3.

Sentinel lymph node sampling in breast cancer

Main articles: Sentinel lymph node and Lymph node metastasis

General

• Selective sampling of lymph nodes.
• Used for staging.
• Positive LNs = poorer prognosis.

Notes:

• If there is no palpable disease, there is no mortality benefit from axillary lymph node dissection, i.e. positive axillary lymph nodes can be left in situ without affecting outcome.
  • This does not negate the fact that a positive sentinel LN biopsy (vs. negative sentinel LN biopsy) portends a poorer prognosis.

Microscopic

Features:

• Atypical cells.
  • Nuclear changes of malignancy:
    • Nuclear enlargement + variation in size.
    • Variation in shape.
    • Hyperchromasia and variation in staining.
  • Usually in the subcapsular sinuses.

Pitfalls:

• Naevus cell rests.

IHC

Some hospitals use:

• CAM5.2 (LMWK) - to look for isolated tumour cells and small lymph node metstases.

Note:

• This is falling out of favour. The prognostic significance of isolated tumour cells is measurable but relatively small.^{[citation needed]}

M stage

Distant metastasis:

• cM0(i+) <=0.2 mm focus of tumour cells, without clinical signs and symptoms.
• pM1 focus of tumour cells > 0.2 mm.

See also

• Invasive breast cancer.
• Breast cancer grading.
• Cancer staging systems.