Table 4 Univariate and multivariate analyses concerning ICMFS: PS = performance status, GK = gamma knife, WBRT = whole brain radiotherapy. Other = Colon (1), jejunum (1), rectosigmoid (2), esophagus (1), endometrium (1), ovary (1), Sarcoma (1), pancreas (1), prostate (1), thyroid

Univariate analysis

Initial PS

0.86

0.37–1.97

0.72

Primary

 Kidney vs lung

 Other vs lung

Extracranial metastasis at diagnosis

0.54

No

1

Yes

1.31

0.54–3.19

Brain metastasis as first sign of cancer

No

0.37

Yes

1

1.44

0.63–3.29

Number of initial brain metastases

1.44

0.93–2.23

0.09

Previous GK treatment

1.13

0.26–4.94

0.86

Previous WBRT treatment

0.53

0.07–4.05

0.54

BSBM

0.78

0.50–1.22

0.28

GPA

0.59

0.34–1.03

0.06

RPA

0.99

0.37–2.62

0.98

Age at time of treatment

0.99

0.94–1.03

0.73

Subtentorial location

1

0.23

Supratentorial location

1.76

0.69–4.48

Size of preoperative lesion

1.63

0.51–5.14

0.4

Time between surgery-GK

0.99

0.97–1.00

0.32

Volume lesion treated with GK

0.91

0.83–1.01

0.09

Dose GK treatment

1.12

0.94–1.33

0.19

Other existing lesions treated at the same time with GK

1.16

1.005–1.34

0.04

Multivariate analysis taking variables with p < 0.2 in univariate analysis + use of Increasing automatic selection technique

Primary lesions

 Kidney vs lung

1.04

0.23–4.69

0.95

 Other vs lung

8.04

1.82–35.4

0.006

Other existing lesions treated at the same time with GK

1.17

1.00–1.37

0.05