Table 1 Baseline characteristics of the exploratory and validation cohorts treated with letrozole and palbociclib
Characteristics | Validation cohort | Exploratory cohort | P value |
|---|---|---|---|
(N = 410) | (N = 221) | ||
Age |  |  | < 0.001 |
 Median | 62 (30–89) | 55 (27–87) |  |
 < 65 years old | 248 (60.5%) | 174 (78.7%) |  |
 ≥ 65 years old | 162 (39.5%) | 47 (21.3%) |  |
 < 55 years old | 98 (23.9%) | 103 (46.6%) |  |
 ≥ 55 years old | 312 (76.1%) | 118 (53.4%) |  |
Race |  |  | < 0.001 |
 White | 320 (78%) | 4 (1.8%) |  |
 Asian | 59 (14.4%) | 216 (97.7%) |  |
 Black | 7 (1.7%) | 0 (0.0%) |  |
 Other | 24 (5.9%) | 1 (0.5%) |  |
Initial stage | Â | Â | 0.002 |
 I | 48 (11.7%) | 31 (14.0%) |  |
 II | 124 (30.2%) | 66 (29.9%) |  |
 III | 69 (16.8%) | 26 (11.8%) |  |
 IV | 127 (31.0%) | 91 (41.2%) |  |
 N/A | 42 (10.2%) | 7 (3.2%) |  |
Recurrence type | Â | Â | 0.034 |
 Locoregional | 9 (2.2%) | 5 (2.3%) |  |
 Distant | 274 (66.8%) | 125 (56.6%) |  |
 Newly diagnosed | 127 (31.0%) | 91 (41.2%) |  |
Disease-free interval | Â | Â | 0.120 |
 Newly metastatic disease | 155 (37.8%) | 102 (46.2%) |  |
 ≤ 12 month | 90 (22.0%) | 44 (19.9%) |  |
 > 12 month | 165 (40.2%) | 75 (33.9%) |  |
Disease site | Â | Â | 0.135 |
 Visceral | 197 (48.0%) | 123 (55.7%) |  |
 Nonvisceral | 213 (52.0%) | 98 (44.3%) |  |
 Bone-only | 96 (23.4%) | 44 (19.9%) |  |
Number of disease sites | Â | Â | 0.826 |
 1 | 129 (31.5%) | 70 (31.7%) |  |
 2 | 106 (25.9%) | 64 (29.0%) |  |
 3 | 101 (24.6%) | 50 (22.6%) |  |
 ≥ 4 | 74 (18.0%) | 37 (16.7%) |  |