A Prospective Comparison of 18F-FDG PET/CT and CT as Diagnostic Tools to Identify the Primary Tumor Site in Patients with Extracervical Carcinoma of Unknown Primary Site

Abstract

Background. The aim of the present study was to evaluate prospectively the diagnostic value of 18 F-fluorodeoxyglu- cosepositronemissiontomography/computedtomography ( 18 F-FDG PET/CT) and conventional CT regarding the ability to detect the primary tumor site in patients with ex- tracervical metastases from carcinoma of unknown pri- mary (CUP) site. Patients and Methods. From January 2006 to December 2010,136newlydiagnosedCUPpatientswithextracervical metastases underwent 18 F-FDG PET/CT. Astandardofreference(SR)wasestablishedbyamul- tidisciplinary team to ensure that the same set of criteria were used for classification of patient s, that is, either as CUP patients or patients with a suggested primary tu- mor site. The independently obtained suggestions of pri- mary tumor sites using PET/CT and CT were correlated with the SR to reach a consensus regarding true-positive (TP), true-negative, false-negative, and false-positive re- sults. Results.SRidentifiedaprimarytumorsitein66CUPpa- tients (48.9%). PET/CT identified 38 TP primary tumor sites and CT identified 43 TP primary tumor sites. No sta- tistically significant differences were observed between 18 F-FDG PET/CT and CT alone in regard to sensitivity, specificity, and accuracy. Conclusion. In the general CUP population with multi- ple extracervical metastases 18 F-FDG PET/CT does not represent a clear diagnostic advantage over CT alone re- garding the ability to detect the primary tumor site. The Oncologist. © AlphaMed Press.