Breast cancer: prognostic factors and staging
- Topic
Stage tells how far a breast cancer has gone; its receptors tell which treatments will work. Together they shape the outlook and the plan.
What it is
The outcome of breast cancer depends above all on its stage: the size of the tumour, the number of involved lymph nodes and whether there are distant metastases. Grade, histologic type, lymphovascular invasion and proliferation refine the prognosis. Predictive factors tell which therapies will work: estrogen and progesterone receptors predict response to endocrine therapy, and HER2 overexpression or amplification predicts response to HER2-targeted drugs. Multigene expression tests estimate recurrence risk in ER-positive cancers and help decide on chemotherapy.
Key facts
- Treatment combines surgery (breast-conserving with radiation, or mastectomy), axillary staging and systemic therapy chosen by receptors.
- Endocrine therapy uses estrogen receptor blockers or aromatase inhibitors; HER2-positive tumours receive antibodies or kinase inhibitors against HER2.
- Treatment before surgery (neoadjuvant) is common for HER2-positive and triple-negative tumours; a complete pathologic response predicts a good outcome.
What each factor tells the clinician
| Factor | How it is measured | Prognostic, predictive or both |
|---|---|---|
| Tumour size and skin or chest wall invasion (T) | Pathology and imaging | Prognostic |
| Lymph node metastases (N) | Sentinel node, axillary dissection | Prognostic (strongest in operable disease) |
| Distant metastases (M) | Imaging, biopsy | Prognostic |
| Histologic grade | Nottingham score | Prognostic |
| ER and PR | Immunohistochemistry | Both: predicts endocrine response |
| HER2 | Immunohistochemistry and in situ hybridisation | Both: predicts anti-HER2 response |
| Ki-67 and gene-expression panels | Immunostain, RNA profiling | Prognostic, guides chemotherapy in ER-positive disease |
| Response to treatment given before surgery | Pathology of the surgical specimen | Prognostic |
Clinical notes
- Accurate pathology reports with size, grade, margins, nodes, ER, PR, HER2 and Ki-67 are the base of every treatment decision.
- Delays in pathology and receptor testing postpone treatment; timely access is a key quality problem in many health systems.
Test yourself
Think of the answer, then tap the question to see it.
What is the difference between a prognostic and a predictive factor?
A prognostic factor estimates outcome regardless of treatment; a predictive factor estimates response to a particular therapy.
What happens to a HER2 immunostain scored 2+?
It is equivocal and is tested by in situ hybridisation for ERBB2 amplification.
Why is a sentinel lymph node biopsy performed?
To stage the axilla through the first draining node; if it is negative, full axillary dissection and its lymphoedema risk can be avoided.
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Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Breast Cancer Treatment (PDQ®)–Health Professional Version (National Cancer Institute, 2026).
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Representative model, for educational purposes only.