Table 4.
Baseline patient characteristics in relation to synchronous or metachronous metastases.
| Baseline BC characteristics | No. patients (n = 220) |
Synchronous BM (n = 49) No. (%) |
Metachronous BM (n = 171) No. (%) |
p-value |
|---|---|---|---|---|
| Age at diagnosis of bone metastasis, years | ||||
| < 65 | 133 (49.1) | 32 (24.1) | 101 (75.9) | 0.431 |
| ≥ 65 | 87 (50.9) | 17 (19.5) | 70 (80.5) | |
| pT at primary diagnosis of breast cancer | ||||
| T0–T2 | 161 (85.0) | 27 (16.8) | 134 (83.2) | < 0.001 |
| T3–T4 | 28 (15.0) | 15 (53.6) | 13 (46.4) | |
| pN at primary diagnosis of breast cancer | ||||
| N0 | 48 (25.6) | 2 (4.2) | 46 (95.8) | 0.001 |
| N+ | 137 (74.3) | 34 (24.5) | 105 (75.5) | |
| Stage at diagnosis of primary disease | ||||
| I | 28 (14.1) | 0 (0.0) | 28 (100.0) | – |
| II | 68 (34.4) | 0 (0.0) | 68 (100.0) | |
| III | 42 (21.2) | 0 (0.0) | 42 (100.0) | |
| IV | 60 (30.3) | 49 (81.7) | 11 (18.3) | |
| Unknown | 22 | – | 22 | |
| Breast cancer molecular subtype | ||||
| Luminal A | 35 (18.8) | 7 (20.0) | 28 (80.0) | 0.315 |
| Luminal B | 118 (63.4) | 31 (26.3) | 87 (73.7) | |
| Basal-like | 8 (4.3) | 1 (12.5) | 7 (87.5) | |
| HER+ | 25 (13.4) | 10 (40.0) | 15 (60.0) | |
| Unknown | 34 | – | 34 | |
| Median Ki67% (interquartile range) | 20 (10–31) | 23 (15–35) | 16 (10–30) | 0.087 |
| ER | ||||
| Negative | 21 (9.9) | 2 (9.5) | 19 (90.5) | 0.114 |
| Positive | 183 (90.1) | 47 (25.7) | 136 (74.3) | |
| Unknown or not performed | 16 | – | 16 | |
| PgR | ||||
| Negative | 60 (29.4) | 11 (18.3) | 49 (81.7) | 0.220 |
| Positive | 144 (70.6) | 38 (26.4) | 106 (73.6) | |
| Unknown or not performed | 16 | – | 16 | |
| HER2 (IHC or FISH) | ||||
| Negative | 162 (87.1) | 38 (23.5) | 124 (76.5) | 0.057 |
| Positive | 24 (12.9) | 10 (41.7) | 14 (58.3) | |
| Unknown or not performed | 34 | 1 | 33 | |
BM bone metastasis, pT primary tumour, pN pathological lymph node, ER oestrogen receptor, PgR progesterone receptor, IHC immunohistochemistry, FISH fluorescence in situ hybridisation.