Table 1.
Clinicopathological characteristics and treatment status of patients treated with CDK4/6 inhibitors
| Group A (n = 34) | Group B (n = 20) | Group C (n = 32) | |||||
|---|---|---|---|---|---|---|---|
| Median age, years (IQR)* | 63 | (58–69) | 70 | (61–77)** | 63 | (53–71) | |
|
| |||||||
| Performance status, n (%)* | 0 | 25 | (73) | 9 | (45) | 19 | (60) |
| 1 | 8 | (24) | 7 | (35) | 12 | (37) | |
| 2 | 1 | (3) | 4 | (20) | 0 | (0) | |
| 3 | 0 | (0) | 0 | (0) | 1 | (3) | |
|
| |||||||
| Breast cancer type, n (%) | Invasive ductal carcinoma | 29 | (85) | 19 | (95) | 31 | (97) |
| Invasive lobular carcinoma | 4 | (12) | 0 | (0) | 1 | (3) | |
| Others | 1 | (3) | 1 | (5) | 0 | (0) | |
|
| |||||||
| Stage, n (%) | I | 3 | (9) | 2 | (10) | 5 | (16) |
| II | 13 | (38) | 4 | (20) | 10 | (31) | |
| III | 10 | (29) | 2 | (10) | 5 | (16) | |
| IV | 8 | (24) | 12 | (60)*** | 12 | (37) | |
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| Nodal involvement, n (%) | N0 | 7 | (21) | 2 | (10) | 9 | (28) |
| N1 | 11 | (32) | 10 | (50) | 10 | (31) | |
| N2 | 3 | (9) | 1 | (5) | 7 | (22) | |
| N3 | 12 | (35) | 7 | (35) | 6 | (19) | |
| Not evaluated | 1 | (3) | 0 | (0) | 0 | (0) | |
|
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| Histological grade, n (%) | I | 7 | (21) | 5 | (25) | 6 | (19) |
| II | 18 | (53) | 11 | (55) | 15 | (47) | |
| III | 3 | (9) | 3 | (15) | 3 | (9) | |
| Not evaluated | 6 | (17) | 1 | (5) | 8 | (25) | |
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| |||||||
| Metastasis sites, n (%)* | Nonvisceral metastases | 16 | (47) | 7 | (35) | 6 | (19)*** |
| Visceral metastases | 18 | (53) | 13 | (65) | 26 | (81)*** | |
| Metastatic sites ≥3 | 5 | (15) | 6 | (30) | 15 | (47)*** | |
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| History of chemotherapy, n (%)* | Neoadjuvant or adjuvant therapy | 17 | (50) | 5 | (20) | 12 | (38) |
| Chemotherapy for MBC | 4 | (12) | 6 | (30) | 18 | (56)*** | |
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| History of endocrine therapy, n (%)* | Neoadjuvant or adjuvant therapy | 19 | (51) | 8 | (40) | 19 | (59) |
| Endocrine therapy for MBC | 26 | (76) | 13 | (65) | 32 | (100)*** | |
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| Type of CDK4/6 inhibitors, n (%)* | Palbociclib | 24 | (71) | 16 | (80) | 25 | (78) |
| Abemaciclib | 10 | (29) | 4 | (20) | 7 | (22) | |
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| |||||||
| Treatment line of CDK4/6 inhibitors, n (%)* | 1 | 8 | (23) | 7 | (35) | 0 | (0)*** |
| 2 | 8 | (23) | 4 | (20) | 6 | (19) | |
| 3 | 11 | (33) | 2 | (10)*** | 7 | (22) | |
| ≥4 | 7 | (21) | 7 | (35) | 19 | (59)*** | |
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| Best overall response for CDK4/6 inhibitors, n (%) | Partial response | 5 | (15) | 4 | (20) | 3 | (9) |
| Stable disease | 23 | (68) | 11 | (55) | 23 | (72) | |
| Progressive disease | 6 | (17) | 2 | (10) | 5 | (16) | |
| Not evaluated | 0 | (0) | 3 | (15) | 1 | (3) | |
|
| |||||||
| PFS of CDK4/6 inhibitors, n (%) | ≥6 months | 15 | (44) | 11 | (55) | 18 | (56) |
| <6 months | 19 | (56) | 9 | (45) | 14 | (44) | |
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| Reason for stopping CDK4/6 inhibitors, n (%) | Disease progression | 30 | (88) | 17 | (85) | 30 | (94) |
| Adverse events | 4 | (12) | 3 | (15) | 2 | (6) | |
IQR, interquartile range; MBC, metastatic breast cancer; PFS, progression-free survival.
*
At the point of stopping CDK4/6 inhibitors.
**
Mann-Whitney U test, p < 0.05.
***
Fisher's exact test, p < 0.05.