Role of 2-Fluoro-2-Deoxyglucose PET/Computed Tomography in Carcinoma of Unknown Primary.

FDG-PET/CT is a potentially useful imaging modality in the setting of Carcinoma of Unknown Primary (CUP) from various aspects. The central question is detection of site of primary, where most studies have documented the pooled sensitivity and specificity of FDG PET/CT in the range of 80%-85% and a tumor detection rate (after the failure of conventional imaging procedures) between 30%-37%. The heterogeneity in the (i) population studied and (ii) criteria used for labelling patient as of unknown primary, have been the prime reason for widely varying result amongst various studies. Initiating appropriate treatment strategies owing to simultaneous whole body disease staging can be regarded an added utility PET/CT, even in the case of failure of primary tumor detection. FDG-PET/CT changed the patient management in around 35% of patients (studies reporting heterogeneous results ranging from 18.2% to 60%). The futuristic approach will be to monitor molecular targeted and cystostatic therapies with FDG-PET/CT which obviously has advantages than anatomical imaging alone.