Table 1 Patient characteristics

  - chemotherapy

42%

n = 303

  - antihormonal therapy

45%

n = 320

  - radiation

47%

n = 333

Disease free survival from initial diagnosis of breast cancer to metastasis

  - median

32.5 months

  - < 24 months

42%

n = 303

  - ≥ 24 months

58%

n = 413

Age at diagnosis of metastasis

  - median

61 years

  - < 50 years

20%

n = 146

  - 50–70 years

56%

n = 402

  - >70 years

23%

n = 168

Menopausal status at time of metastasis

  - premenopausal

19%

n = 134

  - postmenopausal

80%

n = 572

  - not evaluable

1%

n = 10

Hormone-receptor status

  - negative

16%

n = 117

  - positive

79%

n = 563

  - not evaluable

5%

n = 36

Her2 status

  - negative

52%

n = 369

  - positive

20%

n = 145

  - not evaluable

28%

n = 202

Comorbidities at time of metastasis

  - Charlson Score 0

81%

n = 578

  - Charlson Score 1 + 2

17%

n = 123

  - Charlson Score >2

2%

n = 13

Metastatic status at initial diagnosis of breast cancer

  - M1

21%

n = 151

  - M0

76%

n = 547

  - not evaluable

3%

n = 18

Localizations of metastases at initial diagnosis of metastasis

  - visceral

47%

n = 335

  - bone

36%

n = 256

  - CNS

4%

n = 29

  - lymph nodes

9%

n = 66

  - others

4%

n = 29

Number of involved organs at initial diagnosis of metastasis

  - 1 localization

69%

n = 493

  - >1 localizations

31%

n = 223