Table 2 Univariate and multivariable analysis of overall survival after 18 Gy stereotactic radiosurgery

Gross tumor volume

≤ 0.3 cm³ (reference)

0.616

0.319

> 0.3 cm³

1.153

0.660, 2.015

1.384

0.730, 2.623

Extracranial metastases

No (reference)

0.007

0.157

Yes

2.411

1.272, 4.567

2.068

0.756, 5.654

Control of primary cancer

No control (reference)

0.086

0.158

Control

0.611

0.348, 1.071

0.618

0.317,1.205

Systemic treatment * 3 months before/after SRS

No (reference)

0.691

0.374

Yes

0.826

0.323, 2.114

0.611

0.206, 1.811

Karnofsky performance score

0.950

0.923, 0.978

< 0.001

0.946

0.902, 0.993

0.024

Number of brain metastases

1.257

1.002, 1.577

0.048

1.187

0.906, 1.555

0.214

Patient age

1.019

0.994, 1.045

0.138

1.005

0.977, 1.034

0.723

Recursive partitioning analysis (RPA)

1.485

0.913, 2.418

0.111

0.915

0.445, 1.885

0.811

Diagnosis-specific graded prognostic assessment (ds-GPA)

0.517

0.365, 0.732

< 0.001

1.023

0.543, 1.926

0.944

Histology

Other (reference)

0.288

0.609

Malignant melanoma/renal cell cancer/sarcoma

0.729

0.408, 1.306

0.828

0.402, 1.707

Cerebral progression outside the planning target volume

No (reference)

0.119

0.534

Yes

1.658

0.878, 3.130

1.285

0.583, 2.831