Table 1.
Baseline characteristics of patients with HER2-positive early-stage and metastatic breast cancer.
| Early-stage breast cancer | Metastatic breast cancer | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| RTZ (n=129) | CT-P6 (n=125) | Total (N=254) | P-value | RTZ (n=65) | CT-P6 (n=38) | Total (N=103) | P-value | ||
| Age, median (range) | 49 (22–75) | 50 (27–71) | 49 (22–75) | 0.447 | 54 (31–76) | 55 (28–79) | 54 (28–79) | 0.695 | |
| Stage IV, n (%) | 0.333 | ||||||||
| De novo | – | – | – | 47 (72.3) | 24 (63.2) | 71 (68.9) | |||
| Recurrent | – | – | – | 18 (27.7) | 14 (36.8) | 32 (31.1) | |||
| Histology, n (%) | <0.001 | 0.117 | |||||||
| IDC | 113 (87.6) | 124 (99.2) | 237 (93.3) | 60 (93.8) | 32 (86.5) | 92 (91.1) | |||
| ILC | 11 (8.5) | 1 (0.8) | 12 (4.7) | 1 (1.6) | 0 (0) | 1 (1.0) | |||
| Other a | 5 (3.9) | 0 | 5 (2.0) | 3 (4.7) | 5 (13.5) | 8 (7.9) | |||
| ER, n (%) | 0.752 | 0.804 | |||||||
| Positive | 44 (34.1) | 45 (36.0) | 89 (35.0) | 29 (44.6) | 16 (42.1) | 45 (43.7) | |||
| Negative | 85 (65.9) | 80 (64.0) | 165 (65.0) | 36 (55.4) | 22 (57.9) | 58 (56.3) | |||
| PR, n (%) | 0.992 | 0.812 | |||||||
| Positive | 30 (23.3) | 29 (23.2) | 59 (23.2) | 15 (23.1) | 8 (21.1) | 23 (22.3) | |||
| Negative | 99 (76.7) | 96 (76.8) | 195 (76.8) | 50 (76.9) | 30 (78.9) | 80 (77.7) | |||
| Subgroup, n (%) | 0.852 | 0.804 | |||||||
| HR+/HER2+ | 45 (34.9) | 45 (36.0) | 90 (35.4) | 29 (44.6) | 16 (42.1) | 45 (43.7) | |||
| HR−/HER2+ | 84 (65.1) | 80 (64.0) | 164 (64.6) | 36 (55.4) | 22 (57.9) | 58 (56.3) | |||
| HG, b n (%) | 0.960 | 0.135 | |||||||
| 1 or 2 | 68 (73.1) | 83 (72.8) | 151 (72.9) | 4 (36.4) | 7 (70.0) | 11 (52.4) | |||
| 3 | 25 (26.9) | 31 (27.2) | 56 (27.1) | 7 (63.6) | 3 (30.0) | 10 (47.6) | |||
| Ki67, b n (%) | 0.005 | 0.647 | |||||||
| <14 | 23 (29.5) | 12 (12.5) | 35 (20.1) | 3 (11.1) | 3 (11.5) | 6 (11.3) | |||
| ≥14 | 55 (70.5) | 84 (87.5) | 139 (79.9) | 24 (88.9) | 23 (88.5) | 47 (88.7) | |||
| cT, c n (%) | 0.139 | ||||||||
| 1 or 2 | 85 (65.9) | 93 (74.4) | 178 (70.1) | – | – | – | |||
| ≥3 | 44 (34.1) | 32 (25.6) | 76 (29.9) | – | – | – | |||
| cN, d n (%) | 0.072 | ||||||||
| Negative | 16 (12.4) | 26 (20.8) | 42 (16.5) | – | – | – | |||
| Positive | 113 (87.6) | 99 (79.2) | 212 (83.5) | – | – | – | |||
| Metastasis site, n (%) | |||||||||
| Distant LN | – | – | – | 39 (60.0) | 19 (50.0) | 58 (56.3) | 0.323 | ||
| Bone | – | – | – | 33 (50.8) | 16 (42.1) | 48 (47.6) | 0.396 | ||
| Lung | – | – | – | 21 (32.3) | 14 (36.8) | 35 (34.0) | 0.639 | ||
| Liver | – | – | – | 18 (29.2) | 14 (36.8) | 33 (32.0) | 0.424 | ||
| Breast skin | – | – | – | 4 (6.2) | 6 (15.8) | 10 (9.7) | 0.107 | ||
| Brain | – | – | – | 4 (6.2) | 3 (7.9) | 7 (6.8) | 0.513 | ||
| Pleural | – | – | – | 3 (4.6) | 4 (10.5) | 7 (6.8) | 0.225 | ||
| Other e | – | – | – | 9 (13.8) | 2 (5.3) | 11 (10.7) | 0.151 | ||
Other histology included micropapillary, apocrine, mucinous, and metaplastic carcinoma.
Values were missing for some patients across groups.
cT was based on tumor size measured by pre-treatment breast magnetic resonance imaging.
cN positive was defined as axillary lymph node metastasis proven by fine-needle aspiration biopsy (FNAB), or suspicious axillary lymph node metastasis in the imaging study among patients who did not receive FNAB.
Other metastasis sites included adrenal gland, peritoneum, and soft tissue mass.
cN, clinical node stage; cT, clinical tumor stage; ER, estrogen receptor; HER2, human epidermal growth factor receptor 2; HG, histologic grade; HR, hormone receptor; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; LN, lymph node; PR, progesterone receptor; RTZ, reference trastuzumab.