Table 1.
Characteristics of the breast cancer patients in the discovery and validation cohorts
| Discovery cohort n (%) | Validation cohort n (%) | P-valuea | |
|---|---|---|---|
| Number of patients | 413 | 108 | |
| T class | 0.211 | ||
| T1 | 274 (66.3%) | 67 (62.0%) | |
| T2 | 121 (29.3%) | 40 (37.1%) | |
| T3 | 16 (3.9%) | 1 (0.9%) | |
| T4 | 2 (0.5%) | 0 | |
| N class | 0.518 | ||
| N0 | 252 (61.0%) | 67 (62.0%) | |
| N1 | 113 (27.4%) | 27 (25.0%) | |
| N2 | 36 (8.7%) | 13 (12.0%) | |
| N3 | 12 (2.9%) | 1 (1.0%) | |
| Histopathology | 0.372 | ||
| Ductal | 317 (76.8%) | 81 (75.0%) | |
| Lobular | 61 (14.8%) | 21 (19.4%) | |
| Other | 35 (8.5%) | 6 (5.6%) | |
| Histopathological grade | 0.462 | ||
| Grade 1 | 72 (17.4%) | 20 (18.5%) | |
| Grade 2 | 197 (47.7%) | 58 (53.7%) | |
| Grade 3 | 127 (30.8%) | 25 (23.1%) | |
| Unknown | 17 (4.1%) | 5 (4.6%) | |
| ERb expression | 0.008 | ||
| 0% | 75 (18.6%) | 7 (6.5%) | |
| 1–9% | 9 (2.2%) | 5 (4.6%) | |
| 10–59% | 19 (4.6%) | 3 (2.8%) | |
| > 59% | 308 (74.6%) | 92 (85.2%) | |
| Unknown | 2 (0.5%) | 1 (0.9%) | |
| PR expression | 0.304 | ||
| 0% | 107 (25.9%) | 19 (17.6%) | |
| 1–9% | 57 (13.8%) | 13 (12.0%) | |
| 10–59% | 44 (10.7%) | 15 (13.9%) | |
| > 59% | 202 (48.9%) | 60 (55.6%) | |
| Unknown | 3 (0.7%) | 1 (0.9%) | |
| HER2 amplification | 0.007 | ||
| HER2 positive | 51 (12.3%) | 4 (3.7%) | |
| HER2 negative | 362 (87.7%) | 104 (96.3%) | |
| Ki-67 expression | 0.959 | ||
| < 5% | 26 (6.3%) | 7 (6.5%) | |
| 5–14% | 188 (45.5%) | 54 (50%) | |
| 15–30% | 96 (23.3%) | 24 (22.2%) | |
| > 30% | 96 (23.3%) | 22 (20.4%) | |
| Unknown | 7 (1.6%) | 1 (0.9%) | |
| Tumour type | 1.000 | ||
| Unifocal | 324 (78.5%) | 85 (78.7%) | |
| Multifocal | 89 (21.5%) | 23 (21.3%) | |
| Breast cancer subtypes | 0.012 | ||
| Luminal A-like | 187 (45.3%) | 57 (52.8%) | |
| Luminal B-like (HER2 negative) | 119 (28.8%) | 41 (37.9%) | |
| Luminal B-like (HER2 positive) | 27 (6.5%) | 2 (1.9%) | |
| HER2 positive, non-luminal | 23 (5.6%) | 2 (1.9%) | |
| Triple-negative | 50 (12.1%) | 5 (4.6%) | |
| Unknown | 7 (1.7%) | 1 (0.9%) |
aFisher´s exact test
bER, estrogen receptor; PR, progesterone receptor; HER2, human epidermal growth factor receptor-2