Table 1 Summary of clinical and tumor attributes

Number of patients

71

Age, years (median, range)

71

45

31–71

Menopausal status

70

 Premenopause

41 (59%)

 Postmenopause

29 (41%)

Pathologic subtype

71

 IDC

67 (94%)

 ILC

2 (3%)

 Etc. and unknown

2 (3%)

Breast cancer family history

53

 Yes

6 (11%)

 No

47 (89%)

BRCA1/2 pathogenic mutation^a

64

 Wild-type

56 (88%)

 Mutated

8 (12%)

Endocrine therapy

71

 Letrozole

48 (68%)

 Letrozole + GnRH agonist

2 (3%)

 Exemestane + GnRH agonist

14 (20%)

 Fulvestrant

7 (10%)

Progressive disease event

51 (72%)

PFS, months

71

15

95% CI (8.6, 20.4)

 < 6

20 (28%)

 6–20

32 (45%)

 ≥ 20

19 (27%)

Metastasis

71

 De novo

32 (45%)

 Relapsed

39 (55%)

RECIST tumor response

71

 Complete response

3 (4%)

 Partial response

29 (41%)

 Stable disease

27 (38%)

 Progressive disease

12 (17%)

Palliative line of palbociclib

71

 First line

55 (77%)

 Second and later lines

16 (23%)

Follow-up from palbociclib treatment (months)

71

20

3–48