Table 1 Baseline clinical and pathological characteristics
|  | Patients with evaluable tissue (n = 124) | |
|---|---|---|
n | % | |
Age at diagnosis MBC, no (%) | ||
 ≤ 50 years | 60 | 48 |
 > 50 years | 64 | 52 |
Time till MBC, no (%) | ||
 de novo MBC | 30 | 24 |
 ≤ 36 months | 45 | 36 |
 > 36 months | 49 | 40 |
ER-status at diagnosis, no. (%) | ||
 ER-positive | 68 | 55 |
 ER-negative | 56 | 45 |
PR-status at diagnosis* | ||
 PR-positive | 45 | 36 |
 PR-negative | 76 | 61 |
HER2 IHC* | ||
 1+ | 1 | 1 |
 2+ | 12 | 10 |
 3+ | 107 | 86 |
Grade primary tumor* | ||
 Grade 1 or 2 | 34 | 27 |
 Grade 3 | 66 | 53 |
 Grade unknown | 24 | 19 |
Single-organ metastases, no. (%) | ||
 Metastases in a single organ | 72 | 58 |
 Metastases in more organs | 52 | 42 |
Oligo-metastases (≤ 3 metastases), no. (%) | ||
 Oligo-metastases†| 39 | 31 |
 Multiple metastases | 85 | 69 |
Location of metastases at diagnosis MBC, no. (%) | ||
 Bone | 60 | 48 |
 Liver | 44 | 35 |
 Lymph nodes | 45 | 36 |
 Lung | 36 | 29 |
 Skin | 10 | 8 |
 CNS | 14 | 11 |
Prior neoadjuvant/adjuvant trastuzumab, no. (%) | ||
 Yes | 29 | 23 |
 No | 95 | 77 |
Moment first trastuzumab for MBC, no. (%) | ||
 Trastuzumab received in 1st line | 95 | 77 |
 Trastuzumab received in 2nd line | 29 | 23 |
Received pertuzumab for MBC, no (%) | ||
 Yes | 0 | 0 |
 No | 124 | 100 |