Breast cancer staging

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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:[1][2]

  • 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.

N stage

Sampling usually selective, i.e. sentinel lymph nodes only. ===Indications for lymph node sampling===[3]

  • 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:[4]

  • 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".[4] 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:[5]

  • 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

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.[6]
    • 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.[7]

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

References

  1. URL: http://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-staging. Accessed on: 8 July 2010.
  2. URL: http://www.cancerhelp.org.uk/type/breast-cancer/treatment/tnm-breast-cancer-staging. Accessed on: 9 July 2010.
  3. URL: http://www.cap.org/apps/docs/committees/cancer/cancer_protocols/2009/InvasiveBreast_09protocol.pdf. Accessed on: 2 April 2012.
  4. 4.0 4.1 URL: http://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-staging. Accessed on: 8 July 2010.
  5. URL: http://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-staging. Accessed on: 8 July 2010.
  6. Giuliano AE, Hunt KK, Ballman KV, et al. (February 2011). "Axillary dissection vs no axillary dissection in women with invasive breast cancer and sentinel node metastasis: a randomized clinical trial". JAMA 305 (6): 569–75. doi:10.1001/jama.2011.90. PMID 21304082.
  7. URL: http://www.breastpathology.info/Case_of_the_month/2007/COTM_1107%20discussion.html. Accessed on: 28 November 2010.