Table 1.
Baseline and clinical characteristics of patients with lung metastasis.
| Characteristic | Unadjusted | sIPTW | PSM | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Palbociclib + AI (n = 326) |
AI Alone (n = 296) |
Std Diff |
Palbociclib + AI (n = 356) |
AI Alone (n = 292) |
Std Diff |
Palbociclib + AI (n = 173) |
AI Alone (n = 173) |
Std Diff |
|
| Age at mBC diagnosis, years a | |||||||||
| Mean (SD) | 67.0 (10.5) | 71.0 (9.8) | −0.3941 | 68.6 (11.1) | 69.1 (10.1) | −0.0521 | 68.6 (10.3) | 69.9 (9.4) | −0.1408 |
| Median (IQR) | 68 (15) | 72 (16) | 69 (15) | 70 (16) | 69 (16) | 70 (15) | |||
| Female sex a n (%) | 323 (99.1) | 290 (98.0) | −0.0919 | 348 (97.9) | 288 (98.4) | 0.0378 | 172 (99.4) | 172 (99.4) | 0.0000 |
| Race a n (%) | |||||||||
| White | 218 (66.9) | 183 (61.8) | 0.1055 | 234 (65.9) | 192 (65.6) | 0.0050 | 113 (65.3) | 117 (67.6) | −0.0490 |
| Black | 26 (8.0) | 28 (9.5) | −0.0526 | 30 (8.3) | 24 (8.3) | 0.0012 | 14 (8.1) | 14 (8.1) | 0.0000 |
| Other | 82 (25.2) | 85 (28.7) | −0.0804 | 92 (25.8) | 76 (26.1) | −0.0062 | 46 (26.6) | 42 (24.3) | 0.0531 |
| Practice type | |||||||||
| Community | 302 (92.6) | 271 (91.6) | 0.0402 | 327 (92.1) | 269 (91.9) | 0.0047 | 158 (91.3) | 157 (90.8) | 0.0202 |
| Academic | 24 (7.4) | 25 (8.4) | 28 (7.9) | 24 (8.1) | 15 (8.7) | 16 (9.2) | |||
| mBC disease stage at initial diagnosis, n (%) | |||||||||
| I | 40 (12.3) | 37 (12.5) | −0.0070 | 45 (12.7) | 38 (12.9) | −0.0084 | 19 (11.0) | 23 (13.3) | −0.0708 |
| II | 87 (26.7) | 70 (23.6) | 0.0701 | 91 (25.5) | 76 (25.9) | −0.0072 | 50 (28.9) | 44 (25.4) | 0.0780 |
| III | 36 (11.0) | 50 (16.9) | −0.1693 | 49 (13.8) | 41 (13.9) | −0.0051 | 25 (14.5) | 18 (10.4) | 0.1229 |
| IV | 131 (40.2) | 101 (34.1) | 0.1257 | 130 (36.5) | 104 (35.8) | 0.0148 | 62 (35.8) | 65 (37.6) | −0.0360 |
| Not documented | 32 (9.8) | 38 (12.8) | −0.0955 | 41 (11.6) | 34 (11.5) | 0.0020 | 17 (9.8) | 23 (13.3) | −0.1086 |
| ECOG PS a n (%) | |||||||||
| 0 | 126 (38.7) | 62 (20.9) | 0.3945 | 106 (29.7) | 85 (29) | 0.0158 | 43 (24.9) | 41 (23.7) | 0.0270 |
| 1 | 78 (23.9) | 70 (23.6) | 0.0065 | 87 (24.5) | 70 (24.0) | 0.0119 | 48 (27.7) | 43 (24.9) | 0.0657 |
| 2, 3, or 4 | 37 (11.3) | 51 (17.2) | −0.1686 | 51 (14.3) | 43 (14.6) | −0.0081 | 27 (15.6) | 27 (15.6) | 0.0000 |
| Not documented | 85 (26.1) | 113 (38.2) | −0.2614 | 112 (31.4) | 95 (32.4) | −0.0202 | 55 (31.8) | 62 (35.8) | −0.0856 |
| Bone-only metastasis a,b n (%) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Brain metastasis, n (%) | 15 (4.6) | 18 (6.1) | 0.0659 | 14 (3.9) | 23 (7.8) | 0.1686 | 6 (3.5) | 15 (8.7) | 0.2192 |
| Disease-free interval, years a,c n (%) | |||||||||
| De novo mBC | 131 (40.2) | 101 (34.1) | 0.1257 | 130 (36.5) | 104 (35.8) | 0.0148 | 62 (35.8) | 65 (37.6) | −0.0360 |
| ≤1 | 4 (1.2) | 8 (2.7) | −0.1065 | 4 (1.2) | 6 (2.2) | −0.0771 | 3 (1.7) | 2 (1.2) | 0.0485 |
| >1 to 5 | 40 (12.3) | 67 (22.6) | −0.2757 | 48 (13.4) | 69 (23.6) | −0.2627 | 25 (14.5) | 37 (21.4) | −0.1816 |
| >5 | 151 (46.3) | 120 (40.5) | 0.1168 | 174 (48.9) | 112 (38.5) | 0.2110 | 83 (48.0) | 69 (39.9) | 0.1636 |
| Not documented | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| NCI comorbidity index, mean (SD) |
0.28 (0.51) | 0.38 (0.53) | −0.1979 | 0.31 (0.59) | 0.35 (0.50) | −0.0798 | 0.34 (0.61) | 0.34 (0.50) | 0.0097 |
| Number of metastatic sites a,d n (%) | |||||||||
| 1 | 45 (13.8) | 64 (21.6) | −0.2059 | 62 (17.4) | 51 (17.4) | 0.0020 | 25 (14.5) | 23 (13.3) | 0.0334 |
| 2 | 105 (32.2) | 101 (34.1) | −0.0406 | 121 (34.0) | 100 (34.2) | −0.0030 | 64 (37.0) | 60 (34.7) | 0.0482 |
| 3 | 108 (33.1) | 87 (29.4) | 0.0807 | 107 (30.1) | 95 (32.4) | −0.0509 | 54 (31.2) | 59 (34.1) | −0.0617 |
| 4 | 40 (12.3) | 23 (7.8) | 0.1503 | 38 (10.8) | 24 (8.0) | 0.0943 | 17 (9.8) | 17 (9.8) | 0.0000 |
| ≥5 | 28 (8.6) | 21 (7.1) | 0.0556 | 27 (7.7) | 23 (8.0) | −0.0122 | 13 (7.5) | 14 (8.1) | −0.0216 |
| Median follow-up duration (IQR), months | 26.2 (24.8) | 23.0 (30.3) | 25.6 (25.4) | 23.6 (30.2) | 24.0 (24.5) | 24.2 (31.2) | |||
a Variable used in propensity score estimation. b Bone-only disease was defined as metastatic disease in the bone only. c Time from the initial diagnosis to the mBC diagnosis. d Multiple metastases at the same site were counted as one site (e.g., if a patient had three bone metastases in the spine, it was considered only one site). AI, aromatase inhibitor; ECOG PS, Eastern Cooperative Oncology Group performance status; IQR, interquartile range; mBC, metastatic breast cancer; NCI, National Cancer Institute; PSM, propensity score matching; SD, standard deviation; sIPTW, stabilized inverse probability of treatment weighting; Std Diff, standardized difference.