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. 2025 Apr 7;30(4):oyae280. doi: 10.1093/oncolo/oyae280

Table 1.

Baseline characteristics among patients with HER2+ mBC with ≥1 line of therapya

All patients with at least 1L
N = 2074
Patients with HR+mBC and at least 1L
N = 1303
Patients with HR− mBC and at least 1L
N = 720
Age (years) at start of 1L
Median (range) 61 (24-84) 61 (25-84) 60 (24-83)
Age (years) at initial BC diagnosis
Median (range) 58 (23-83) 57 (23-83) 58 (24-83)
Sex
Male 20 (1.0%) 18 (1.4%) 2 (0.3%)
Female 2054 (99.0%) 1285 (98.6%) 718 (99.7%)
Race
White 1301 (62.7%) 826 (63.4%) 441 (61.3%)
Black or African American 246 (11.9%) 141 (10.8%) 100 (13.9%)
Asian 65 (3.1%) 42 (3.2%) 20 (2.8%)
Other 288 (13.9%) 179 (13.7%) 103 (14.3%)
Unknown 174 (8.4%) 115 (8.8%) 56 (7.8%)
Time (days) from initial BC diagnosis to start of 1L
Number of observations 2073 1302 720
Mean (SD) 1058 (1,615) 1180 (1,746) 837 (1,290)
Median (range) 411 (0-15,520) 491 (1-15,520) 298 (0-10,720)
Stage at initial breast cancer diagnosis
I 183 (8.8%) 109 (8.4%) 67 (9.3%)
II 435 (21.0%) 313 (24.0%) 116 (16.1%)
III 425 (20.5%) 248 (19.0%) 166 (23.1%)
IV 891 (43.0%) 546 (41.9%) 321 (44.6%)
Unknown 140 (6.8%) 87 (6.7%) 50 (6.9%)
Number of metastatic sites at any time prior to or at start of 1L
1 867 (41.8%) 552 (42.4%) 290 (40.3%)
2 534 (25.7%) 333 (25.6%) 188 (26.1%)
3 306 (14.8%) 191 (14.7%) 109 (15.1%)
4+ 212 (10.2%) 132 (10.1%) 75 (10.4%)
Unknown 155 (7.5%) 95 (7.3%) 58 (8.1%)
Sites of metastases at any time prior to or at start of 1L
Bone 1068 (51.5%) 746 (57.3%) 297 (41.3%)
Brain 191 (9.2%) 96 (7.4%) 89 (12.4%)
Liver 689 (33.2%) 405 (31.1%) 266 (36.9%)
Lung 650 (31.3%) 382 (29.3%) 254 (35.3%)

Cell entries show n (%), unless otherwise specified.

aFifteen one patients had missing HR status.

Abbreviations: 1L = first-line therapy; BC = breast cancer; HER2+ = human epidermal growth factor receptor 2 positive; HR = hormone receptor; HR- = hormone receptor negative; HR+ = hormone receptor positive; mBC = metastatic breast cancer; SD = standard deviation.