Table 1.
Clinico-pathological data of the study cohort
| Characteristic | All cases, number (%) | Centrally evaluated HER2- positive cases, number (%) |
Centrally evaluated HER2- negative cases, number (%) |
|---|---|---|---|
| Samples, number | 217 | 158 | 59 |
| Local HER2 status (IH/ISH) | |||
| positive | 217 (100) | 158 (100) | 59 (100) |
| negative | 0 (0) | 0 (0) | 0 (0) |
| Central HER2 status (IH/SISH) | |||
| Positive | 158 (72.8) | 158 (100) | 0 (0) |
| Negative | 59 (27.2) | 0 (0) | 59 (100) |
| HER2 protein expression (central IH) | |||
| 3+ | 144 (66.4) | 144 (91.1) | 0 (0) |
| 2+ | 20 (9.2) | 8 (5.1) | 12 (20.3) |
| 0/1+ | 48 (22.1) | 2 (1.3) | 46 (78.0) |
| missing | 5 (2.3) | 4 (2.5) | 1 (1.7) |
| HER2 gene amplification (central SISH) | |||
| SISH positive (>2.2) | 109 (50.2) | 109 (69.0) | 0 (0) |
| SISH negative (<1.8) | 49 (22.6) | 10 (6.3) | 39 (66.1) |
| SISH equivocal (1.8-2.2) | 8 (3.7) | 6 (3.8) | 2 (3.4) |
| missing | 51 (23.5) | 33 (20.9) | 18 (30.5) |
| HER2 mRNA expression (central qPCR) | |||
| Positive (>19.5) | 141 (65.0) | 137 (86.7) | 4 (6.8) |
| Negative (≤19.5) | 76 (35.0) | 21 (13.3) | 55 (93.2) |
| ER/PR Status (local IH) | |||
| ER+ and/or PR+ | 125 (57.6) | 84 (53.2) | 41 (69.5) |
| ER-/PR- | 92 (42.4) | 74 (46.8) | 18 (30.5) |
| ESR1 mRNA expression (central qPCR) | |||
| Positive (>13.8) | 109 (50.2) | 70 (44.3) | 39 (66.1) |
| Negative (≤13.8) | 108 (49.8) | 88 (55.7) | 20 (33.9) |
| Tumor grade | |||
| G1 to G2 | 114 (55.1) | 78 (49.4) | 36 (61.0) |
| G3 | 93 (44.9) | 72 (45.6) | 21 (35.6) |
| Missing | 10 (4.6) | 8 (5.1) | 2 (3.4) |
| Clinical tumor stage | |||
| cT1 to cT2 | 155 (71.4) | 110 (69.6) | 45 (76.3) |
| cT3 to cT4 | 62 (28.6) | 48 (30.4) | 14 (23.7) |
| Clinical nodal status | |||
| cN0 | 83 (38.2) | 61 (38.6) | 22 (37.3) |
| cN+ | 134 (61.8) | 97 (61.4) | 37 (62.7) |
| Pathological response | |||
| No pCR | 131 (60.4) | 84 (53.2) | 47 (79.7) |
| pCR (ypT0/is ypN0) | 86 (39.6) | 74 (46.8) | 12 (20.3) |
| Age group | |||
| ≤ 50 years | 109 (50.2) | 84 (53.2) | 25 (42.4) |
| > 50 years | 108 (49.8) | 74 (46.8) | 34 (57.6) |
| Tumor type | |||
| Ductal/other | 207 (95.4) | 156 (98.7) | 51 (86.4) |
| Lobular | 10 (4.6) | 2 (1.3) | 8 (13.6) |
HER2, human epidermal growth factor receptor 2; SISH, silver in situ hybridization; IH: immunohistochemistry; ISH: in situ hybridization; qPCR, quantitative polymerase chain reaction; ypT: tumor stage after neoadjuvant therapy; ypN: nodal status after neoadjuvant therapy.