Appendix 1:
Baseline characteristics (N = 45)
| Characteristic | Number of patients | % |
| Median age, years (range) | 52 (36–73) | |
| Race | ||
| White | 43 | 96 |
| Asian | 1 | 2 |
| Not reported | 1 | 2 |
| ECOG PS | ||
| 0 | 30 | 67 |
| 1 | 15 | 33 |
| Predominant site of disease | ||
| Soft tissue | 11 | 24 |
| Osseous | 5 | 11 |
| Visceral | 28 | 62 |
| Unknown | 1 | 2 |
| Number of metastatic sites | ||
| 3–5 | 7 | 16 |
| 6 | 13 | 29 |
| 7 | 13 | 29 |
| 8–9 | 11 | 24 |
| Unknown | 1 | 2 |
| Estrogen receptor | ||
| Positive | 31 | 69 |
| Negative | 13 | 29 |
| Unknown | 1 | 2 |
| Progesterone receptor | ||
| Positive | 23 | 51 |
| Negative | 20 | 44 |
| Unknown | 2 | 4 |
| Previous adjuvant systemic therapy | ||
| Yes | 33 | 73 |
| No | 11 | 24 |
| Unknown | 1 | 2 |
| Previous hormone therapy | ||
| Yes | 14 | 31 |
| No | 30 | 67 |
| Unknown | 1 | 2 |
| Prior anthracycline | ||
| Adjuvant | 25 | 56 |
| Neoadjuvant | 1 | 2 |
| None | 19 | 42 |
| Prior taxane | ||
| Adjuvant | 17 | 38 |
| Neoadjuvant | 1 | 1 (2) |
| None | 27 | 60 |
| HER2 method of detection | ||
| Immunohistochemistry | 27 | 60 |
| FISH | 15 | 33 |
| Not done | 3 | 7 |
| HER2 status | ||
| Negative | 33 | 73 |
| Not done | 4 | 9 |
| Missing | 8 | 18 |
ECOG PS, Eastern Cooperative Oncology Group performance status; HER2, human epidermal receptor 2.