The Diagnostic Contribution of (18)F-FDG PET/CT Scan in Cancer of Unknown Primary

OBJECTIVE: The aim of the present study was to evaluate the clinically diagnostic contribution of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography(18F-FDG PET/CT) in patients with cancer of unknown primary (CUP). METHODS: The retrospective investigation, cross-sectional analysis of 124 18F-FDG PET/CT scans of patients with CUP between June 2014 and July 2015 was performed. The increased 18F-FDG uptake focus were assessed in correlation with histopathology. The diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive values were assessed for 18F-FDG PET/CT. RESULTS: The 18F-FDG PET/CT successfully detected primary tumor in 56 patients with high 18F-FDG uptake involvement (true positive, 45.2%). 58 patients whose final histopathology and clinically without evidence of a primary tumor (true negative, 46.8%). 8 patients whose final histopathologicallyand clinically without evidence of a primary tumor but high 18F-FDG uptake involvement (false positive, 6.4%). The 18F-FDG PET/CT scan results were negative for primary site localization in only 2 patients with no 18F-FDG uptake involvement (false negative, 1.6%). Generally, the diagnostic accuracy was found to be 91.9%, sensitivity 96.5%, specificity 87.8%, positive predictive value 87.5%, negative predictive value 96.6%, positive likelihood ratio 7.9% and negative likelihood ratio 0.04%. CONCLUSION: It can be said that 18F-FDG PET/CT may be useful in the diagnosis of patients with CUP