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

Abstract

The aim of the present study was to evaluate the clinically diagnostic contribution of 18 Ffluorodeoxyglucose positron emission tomography combined with computed tomography (18 F-FDG PET/CT) in patients with cancer of unknown primary (CUP). Method: The retrospective investigation, cross-sectional analysis of 124 18 F-FDG PET/CT scans of patients with CUP between June 2014 and July 2015 was performed. The increased 18 F-FDG uptake focus were assessed in correlation with histopathology. The diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive values were assessed for 18 F-FDG PET/CT. Results: The 18 F-FDG PET/CT successfully detected primary tumor in 56 patients with high 18 F-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 18 F-FDG uptake involvement (false positive, 6.4%). The 18 F-FDG PET/CT scan results were negative for primary site localization in only 2 patients with no 18 F-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%. Conclusions: It can be said that 18 F-FDG PET/CT may be useful in the diagnosis of patients with CUP.

The impact of 18F-FDG PET/CT in the clinical management of patients with lymph node metastasis of unknown primary origin

“…Previous studies had indicated that the most frequently identified primaries in CUP by 18F-FDG PET/CT were lungs or head and neck carcinoma [14,15], as the results of our study. 18F-FDG PET/CT has proven its usefulness in localizing a primary tumor in the head-neck area compared to contrast-enhanced CT and MRI and could be recommended as an early diagnostic modality in the workup of these patients [16,17].…”