Table 2.
Baseline clinicopathological characteristics according to HER2 status of 1156 HR+ BC patients
| Clinicopathological characteristics | Overall (N = 1156, %) | HER2-null (62, 5.4%) | HER2 ultra-low (320, 27.7%) | HER2-low (774, 66.9%) | P (HER2 status) | |
|---|---|---|---|---|---|---|
| Null vs ultra-low | Ultra-low vs low | |||||
| Age/years | ||||||
| Median/range | 52/24–89 | 53/33–79 | 51/24–85 | 52/25–87 | 0.564* | 0.511* |
| Mean ± SD | 53.1 ± 11.3 | 53.7 ± 11.4 | 52.8 ± 11.1 | 53.3 ± 11.4 | ||
| Menopaual status | ||||||
| Pre/perimenopausal | 656 (56.7) | 32 (51.6) | 185 (57.9) | 439 (56.7) | 0.367 | 0.739 |
| Postmenopausal | 500 (43.3) | 30 (48.4) | 135 (42.1) | 335 (43.3) | ||
| Breast position | ||||||
| Left | 581 (50.3) | 29 (46.8) | 161 (50.3) | 391 (50.5) | 0.610 | 0.951 |
| Right | 575 (49.7) | 33 (53.2) | 159 (49.7) | 383 (49.5) | ||
| Tumor size/cm | ||||||
| Median/range | 2.0/0.3–9 | 2.0/0.6–5.5 | 1.9/0.4–6.5 | 2/0.3–9 | 0.527* | 0.523* |
| Mean ± SD | 2.1 ± 1.0 | 2.2 ± 1.0 | 2.1 ± 1.0 | 2.1 ± 1.1 | ||
| Tumor multiplicity | ||||||
| Single | 1050 (90.8) | 55 (88.7) | 293 (91.6) | 702 (90.7) | 0.470 | 0.650 |
| Multiple | 106 (9.2) | 7 (11.3) | 27 (8.4) | 72 (9.3) | ||
| Histologic type | ||||||
| Ductal | 984 (85.1) | 44 (71.0) | 270 (84.4) | 670 (86.6) | 0.004 | 0.638 |
| Lobular | 59 (5.1) | 10 (16.1) | 16 (5.0) | 33 (4.3) | ||
| Other | 113 (9.8) | 8 (12.9) | 34 (10.6) | 71 (9.1) | ||
| Grade | ||||||
| 1 | 80 (6.9) | 7 (11.3) | 26 (8.1) | 47 (6.1) | 0.156 | 0.389 |
| 2 | 891 (77.1) | 41 (66.1) | 248 (77.5) | 602 (77.8) | ||
| 3 | 185 (16.0) | 14 (22.6) | 46 (14.4) | 125 (16.1) | ||
| pT | ||||||
| 1 | 659 (57.0) | 33 (53.2) | 189 (59.1) | 437 (56.5) | 0.668 | 0.716 |
| 2 | 473 (41.0) | 28 (45.2) | 125 (39.1) | 320 (41.3) | ||
| 3 | 24 (2.0) | 1 (1.6) | 6 (1.8) | 17 (2.2) | ||
| pN | ||||||
| 0 | 143 (12.4) | 8 (12.9) | 37 (11.6) | 98 (12.7) | 0.102 | 0.211 |
| 1 | 240 (20.8) | 10 (16.1) | 56 (17,5) | 174 (22.5) | ||
| 2 | 78 (6.7) | 9 (14.5) | 17 (5.3) | 52 (6.7) | ||
| 3 | 42 (3.6) | 1 (1.6) | 12 (3.7) | 29 (3.7) | ||
| Unknown | 653 (56.5) | 34 (54.9) | 198 (61.9) | 421 (54.4) | ||
| ER expression | ||||||
| Median/range | 90/1–100 | 90/1–95 | 90/1–100 | 90/1–100 | 0.083* | 0.036* |
| Mean ± SD | 79.5 ± 21.9 | 72.0 ± 28.5 | 77.8 ± 23.7 | 80.8 ± 20.3 | ||
| Ki67 | ||||||
| Median/range | 2/1–90 | 2/1–80 | 2/1–90 | 2/1–80 | 0.519 | <0.001* |
| Mean ± SD | 9.4 ± 15.3 | 10.6 ± 18.1 | 12.3 ± 18.0 | 8.1 ± 13.6 | ||
| TILs | ||||||
| Median/range | 5/1–90 | 5/1–70 | 5/1–80 | 5/1–90 | 0.618* | 0.035* |
| Mean ± SD | 12.0 ± 13.1 | 11.6 ± 15.0 | 10.7 ± 11.9 | 12.5 ± 13.4 | ||
| Unknown | 15 | 2 | 6 | 7 | ||
| Type of surgery | ||||||
| BCS/+BR | 292 (25.3) | 11 (17.7) | 85 (26.6) | 196 (25.3) | 0.341 | 0.121 |
| Mastectomy | 349 (30.2) | 23 (37.1) | 107 (33.4) | 219 (28.3) | ||
| Mastectomy + ALND | 515 (44.5) | 28 (45.2) | 128 (40.0) | 359 (46.4) | ||
| Recurrence or metastasis | ||||||
| Yes | 39 (3.4) | 3 (4.8) | 11 (3.4) | 26 (3.4) | 0.483 | 0.948 |
| No | 1117 (96.6) | 59 (95.2) | 309 (96.6) | 748 (96.6) | ||
| Postoperative chemotherapy | ||||||
| Yes | 649 (56.1) | 38 (61.3) | 179 (55.9) | 432 (55.8) | 0.216 | 0.725 |
| No | 498 (43.1) | 22 (35.5) | 138 (43.1) | 338 (43.7) | ||
| Unknown | 9 (0.8) | 2 (3.2) | 3 (1.0) | 4 (0.5) | ||
| Postoperative radiotherapy | ||||||
| Yes | 242 (21.0) | 15 (24.2) | 58 (18.1) | 169 (21.8) | 0.509 | 0.083 |
| No | 897 (77.6) | 46 (74.2) | 254 (79.4) | 597 (77.1) | ||
| Unknown | 17 (1.4) | 1 (1.6) | 8 (2.5) | 8 (1.1) | ||
| Postoperative endocrine therapy | ||||||
| Yes | 980 (84.8) | 49 (79.0) | 273 (85.3) | 658 (85.0) | 0.094 | 0.951 |
| No | 146 (12.6) | 13 (21.0) | 39 (12.2) | 94 (12.2) | ||
| Unknown | 30 (2.6) | 0 (0.0) | 8 (2.5) | 22 (2.8) | ||
BC breast cancer; HR hormone receptor; ER estrogen receptor; TILS tumor infiltrating lymphocytes; BCS breast-conserving surgery; BR breast reconstruction; ALND axillary lymph node dissection; SD standard deviation
Bold indicates P < 0.05
*T-test; other testing methods are Chi-square test or Fisher’s exact test