Table 2.
HER2 re-evaluation by serum HER2, CTC, and metastatic tissue
| Primary tissue | ||||
| HER2 evaluation | Total | HER2 negative | HER2 unknown | HER2 positive |
| Serum HER2 (n = 77) | 77 | 53 | 19 | 5 |
| HER2 negative | 57 | 41 (77) | 15 (79) | 1 (20) |
| HER2 positive | 20 | 12 (23) | 4 (21) | 4 (80) |
| CTC HER2 (n = 21)a | 21 | 12 | 6 | 3 |
| HER2 negative | 13 | 8 (67) | 3 (50) | 2 (67) |
| HER2 positive | 8 | 4 (33) | 3 (50) | 1 (33) |
| Metastatic tissue (n = 10)b | 10 | 8 | 2 | - |
| HER2 negative | 8 | 6 (75) | 2 (100) | - |
| HER2 positive | 2 | 2 (25) | 0 | - |
1Fifty-six patients were circulating tumor cell (CTC) negative; in 10 patients no CTC evaluation could be performed. bMetastatic tissue was only available in 10 patients. HER, human epidermal growth factor receptor.