Table 3.
PR and HER2 status of BRCA1-associated breast cancers
| ER- BRCA1 cancers | ER+ BRCA1 cancers | |
|---|---|---|
| n = 68 | n = 49 | |
| PR positive | 0 | 40 |
| HER2 +* | 0 | 3 (1 IHC, 2 FISH) |
| HER2 negative** | 0 | 34 |
| HER2 equivocal^ | 0 | 2 |
| HER2 unknown | 0 | 1 |
| PR weak positive^^ | 2 | 6 |
| HER2 +* | 0 | 1 (IHC) |
| HER2 -** | 2 | 4 |
| HER2 unknown | 0 | 1 |
| PR negative | 59 | 1 |
| HER2 +* | 3 (IHC) | 0 |
| HER2 -** | 48 | 1 |
| HER2 equivocal^ | 1 (FISH) | 0 |
| HER2 unknown | 7 | |
| PR unknown | 7 | 2 |
| HER2 -** | 6 | 2 |
| HER2 unknown | 1 | 0 |
ER, estrogen receptor; FISH, fluorescence in situ hybridization; HER, human epidermal growth factor receptor; IHC, immunohistochemistry; PR, progesterone receptor; -, negative; +, positive.
* HER2 positive: HER2:CEP17 ratio by FISH >2.2 or IHC 3+ (no FISH performed)
** HER2 negative: HER2:CEP17 ratio by FISH <1.8 or IHC <3+ (no FISH performed)
^HER2 equivocal: HER2:CEP17 ratio by FISH 1.8 to 2.2
^^ Weak PR positive: 1 to 10% cells show nuclear staining for PR