Table 1 Eligibility criteria - inclusions and exclusions

 • Histologically proven malignant cancer

• Primary brain tumour

 • Gadolinium-enhanced volumetric MRI-scan showing 11–20 newly diagnosed BM

• A second active primary tumour

• Small Cell Lung Cancer, Lymphoma, Leukaemia, Meningeal disease

 • Cumulative tumour volume in the brain ≤30 cm³

• Prior brain treatment (radiation/surgery)

 • Lesion > 3 mm from the optic apparatus

• Upfront planned surgery after GKRS

 • Patient age ≥ 18 years

• History of a significant neurological or psychiatric disorder

 • Karnofsky Performance Status ≥70

• Participation in a concurrent study in which neuropsychological or quality of life assessments are involved

 • Anticipated survival ≥3 months

• Underlying medical condition precluding adequate follow-up

 • Patient informed consent obtained (verifying that patients are aware of the investigational nature of this study)

• Patients unable to complete test battery due to any of the following reasons:

 • Patients can be undergoing concurrent systemic therapy at the discretion of their treating oncologist

○ Lack of basic proficiency in Dutch

○ IQ < 85

○ Severe aphasia

○ Paralysis grade 0–3 (MRC scale)

○ Severe visual problems