Table 7. Surrogate definitions of molecular subtypes of breast cancer.
| Molecular Subtypes | Luminal A | Luminal B | HER2 overexpression | Basal-like |
|---|---|---|---|---|
| histopathologic surrogate definition | • ER-positive | HER2-negative | HER2-positive (non-luminal) | Triple-negative (ductal) |
| • HER2-negative | • ER-positive | • HER2-positive | • ER and PR absent | |
| • Ki67 low* | • HER2-negative | • ER and PR absent | • HER2-negative | |
| • PR high** | • and either | |||
| • Ki67 high** or | ||||
| • PR low* | ||||
| HER2-positive | ||||
| • ER-positive | ||||
| • HER2-positive | ||||
| • any Ki67 | ||||
| • any PR |
Notes: *The cut-off point between high and low values for Ki-67 varies among laboratories. **Suggested cut-off values for both PR and Ki-67 are 20%. Abbreviations: ER, oestrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor 2.