Table 1. Baseline characteristics (n=335).
| Characteristic | No. (%) | Characteristic | No. (%) |
|---|---|---|---|
| Age (yr)* | Subtype† | ||
| At diagnosis | 44 (22-85) | HR+/HER2- | 54 (16.1) |
| At first metastasis | 47 (26-85) | HR+/HER2+ | 19 (5.7) |
| Tumor size (cm) | HR-/HER2+ | 28 (8.4) | |
| ≤ 2 | 93 (27.8) | TN | 35 (10.4) |
| > 2 | 242 (72.2) | Unknown | 199 (59.4) |
| Nodal status† | Operation type | ||
| Negative | 94 (28.1) | Mastectomy | 262 (78.2) |
| Positive | 237 (70.7) | Breast-conserving surgery | 73 (21.8) |
| Unknown | 4 (1.2) | Adjuvant chemotherapy | |
| AJCC stage | Yes | 288 (85.9) | |
| DCIS | 2 (0.6) | No | 47 (14.1) |
| I | 40 (11.9) | Adjuvant endocrine therapy | |
| II | 146 (43.6) | Yes | 161 (48.1) |
| III | 147 (43.9) | No | 174 (51.9) |
| Histologic grade† | Adjuvant radiotherapy | ||
| I/II | 204(60.9) | Yes | 138 (41.1) |
| III | 99 (29.6) | No | 197 (58.9) |
| Unknown | 32 (9.5) | Metastasis-free interval (mo)* | 31 (6-200) |
| ER and/or PR status | Short | 133 (40.0) | |
| Positive | 194 (57.9) | Intermediate | 135 (40.0) |
| Negative | 125 (37.3) | Long | 67 (20.0) |
| Unknown | 16 (4.8) | Site of first distant relapse† | |
| HER2 status‡ | Bone | 80 (23.9) | |
| Positive | 47 (14.0) | Liver | 65 (19.4) |
| Negative | 89 (26.6) | Lung | 24 (7.1) |
| Unknown | 199 (58.4) | Brain | 15 (4.5) |
| Ki-67† | CNS | 23 (6.9) | |
| High ( ≥ 20%) | 69 (20.6) | Multiple | 108 (32.2) |
| Low ( < 20%) | 22 (6.6) | Unknown | 20 (6.0) |
| Unknown | 244 (72.8) |
AJCC=American Joint Committee on Cancer; DCIS=ductal carcinoma in situ; ER=estrogen receptor; PR=progesterone receptor; HER2=human epidermal growth factor receptor 2; HR=hormone receptor; TN=triple-negative; CNS=central nervous system.
*Median (range); †Data with missing values; ‡HER2 positivity was defined by a 3+ score on immunohistochemistry or amplification on fluorescence in situ hybridization.