CAR-Study B is a prospective randomized trial comparing cognitive outcome after GKRS or WBRT in eligible patients with 11-20 BM on a triple dose gadolinium-enhanced MRI-scan. Neuropsychological assessment will be performed at baseline and at 3, 6, 9, 12 and 15 months after treatment. Follow-up assessments will be combined with 3-monthly MRI-scans.