Table 2.
Tumor characteristics and anti-HER2 treatment
| Number (n = 38) | ||
|---|---|---|
| Specimen source | Initial core biopsy breast | 20 |
| Initial core biopsy lymph node | 4 | |
| Surgical excision breast | 7 | |
| Surgical excision lymph node | 3 | |
| Distant metastasis biopsy | 4 | |
| Tumor Type/subtype | Ductal | 29 |
| Ductal with lobular features | 2 | |
| Ductal/mucinous | 1 | |
| Ductal/micropapillary | 1 | |
| Ductal with atypical lobular hyperplasia/mucinous | 1 | |
| Lobular | 1 | |
| Neuroendocrine | 1 | |
| Poorly differentiated | 2 | |
| Grade | 1 | 6 |
| 2 | 10 | |
| 3 | 12 | |
| Unknown | 10 | |
| Stage | I | 11 |
| II | 10 | |
| III | 3 | |
| IV | 14 | |
| Hormone status | ER+/PR+ | 18 |
| ER+/PR− | 3 | |
| ER−/PR+ | 4 | |
| ER−/PR− | 13 | |
| HER2/CEP17 ratio | < 2.0a | 1 |
| 2.0–2.9 | 26 | |
| 3.0–5.0 | 7 | |
| > 5.0 | 4 | |
| HER2 copy number | < 4.0a | 1 |
| 4.0–5.9 | 17 | |
| 6.0–9.0 | 12 | |
| > 9.0 | 8 | |
| Anti-HER2 treatment | Trastuzumab | 17 |
| Trastuzumab and pertuzumab | 13 | |
| None | 8 |
aPatients that fell in this category were tested prior to 2018 and considered HER2 positive based on 2013 ASCO–CAP guidelines