18F-FDG PET/CT as a diagnostic tool in patients with extracervical carcinoma of unknown primary site: a literature review

Background.

Carcinoma of unknown primary (CUP) represents a heterogeneous group of metastatic malignancies for which no primary tumor site can be identified after extensive diagnostic workup. Failure to identify the primary site may negatively influence patient management. The aim of this review was to evaluate ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) as a diagnostic tool in patients with extracervical CUP.

Materials and Methods.

A comprehensive literature search was performed and four publications were identified (involving 152 patients) evaluating ¹⁸F-FDG PET/CT in CUP patients with extracervical metastases. All studies were retrospective and heterogeneous in inclusion criteria, study design, and diagnostic workup prior to ¹⁸F-FDG PET/CT.

Results.

¹⁸F-FDG PET/CT detected the primary tumor in 39.5% of patients with extracervical CUP. The lung was the most commonly detected primary tumor site (～50%). The pooled estimates of sensitivity, specificity, and accuracy of ¹⁸F-FDG PET/CT in the detection of the primary tumor site were 87%, 88%, and 87.5%, respectively.

Conclusions.

The present review of currently available data indicates that ¹⁸F-FDG PET/CT might contribute to the identification of the primary tumor site in extracervical CUP. However, prospective studies with more uniform inclusion criteria are required to evaluate the exact value of this diagnostic tool.