Table 1. Baseline characteristics of study patients.
| Variables | Derivation cohort | Validation cohort | P value |
| No. (%) | No. (%) | ||
| No. of patients | 897 | 449 | |
| Age (years) | 58 (48, 66) | 56 (47, 66) | 0.572 |
| T stage | 0.730 | ||
| T1 | 242 (27.0) | 122 (27.2) | |
| T2 | 524 (58.4) | 266 (59.2) | |
| T3 | 111 (12.4) | 48 (10.7) | |
| T4 | 20 (2.2) | 13 (2.9) | |
| N stage | 0.980 | ||
| N0 | 426 (47.5) | 214 (47.6) | |
| N1 | 305 (34.0) | 149 (33.2) | |
| N2 | 94 (10.5) | 47 (10.5) | |
| N3 | 66 (7.3) | 35 (7.8) | |
| Nx | 6 (0.7) | 4 (0.9) | |
| TNM stage | 0.806 | ||
| I | 159 (17.7) | 86 (19.1) | |
| II | 523 (58.3) | 255 (56.8) | |
| III | 205 (22.9) | 105 (23.4) | |
| IV | 10 (1.1) | 3 (0.7) | |
| ER status | 0.998 | ||
| Negative | 187 (20.8) | 93 (20.7) | |
| Positive | 676 (75.4) | 339 (75.5) | |
| Unknown | 34 (3.8) | 17 (3.8) | |
| PR status | 0.801 | ||
| Negative | 241 (26.9) | 117 (26.1) | |
| Positive | 551 (61.4) | 274 (61.0) | |
| Unknown | 105 (11.7) | 58 (12.9) | |
| Her2 status | |||
| Negative | 634 (70.7) | 316 (70.4) | 0.945 |
| Positive | 136 (15.1) | 71 (15.8) | |
| Unknown | 127 (14.2) | 62 (13.8) |
TNM, tumor-node-metastasis; ER, estrogen receptor; PR, progesterone receptor; Her2, human epithelial growth factor receptor 2.