LAUSR

2076Background: Brain metastasis (BM) are the first clinical presentation of cancer in around 30% of patients. They are then referred as BM from cancer of unknown primary site (BM-CUPS). The value of 18F-fluordesoxyglucose positron emission tomography (FDG-PET)/CT has not yet be determined for the management of these patients. Methods: A total of 566 patients were operated for BM at the University Hospital Zurich between 2004 and 2014, of whom 127 were identified as BM-CUPS patients. Two cohorts from other independent centers (n = 100 and 120) were used for the validation of data. Results: No difference in determining the localization of the primary lesion was observed between FDG-PET/CT and CT (FDG-PET/CT: 73/78, 93.6%; CT: n = 70/78, 89.7%; p = 0.25, McNemar’s test). The same pattern of primary lesion and other extracranial lesions was observed in 36 of 64 patients (56.3%). Additional suspicious extracranial metastases were identified by FDG-PET/CT in 28 patients (43.7%). The median graded prognostic as...