The Value Of Whole Body¹⁸F-FDG PET/CT Imaging In Cytologically Proven Metastatic Cervical Carcinoma Of Unknown Primary （CCUP）: A Retrospective Study

BackgroundCarcinoma of unknown primary (CUP) represents a heterogeneous group of metastaticmalignancies for which no primary tumor site can be identified after extensive routinediagnostic workup. Failure at this level has led to patients being referred for a whole body18F-FDG PET/CT scan in attempt to localize the primary site.PurposeThe aim of this study was to assess the potential of1F-fluorodeoxyglucose (1FDG) wholebody positron emission tomography/computed tomography (PET/CT) imaging, in patientsreferred with metastatic cervical carcinomas of unknown primaries (CCUP), in detectingthe primary tumor and concomitant metastases as well as to investigate the presence of anyprognostic factors to this heterogeneous group of tumors.Materials and methodsEighty consecutive patients with cervical metastasis of CUP (CCUP) who had previouslyundergone PET/CT between January2010and September2012were retrospectivelyanalyzed. All patients had histologically proven cervical metastatic carcinomas and relevantdiagnostic workup prior to18F-FDG PET/CT failed to detect a primary tumor. All the patientsincluded have full follow-up material. The average time of follow-up was of16months,ranging from4to34months. The golden standard used was the final clinical diagnosis.ResultsWhole body18F-FDG PET/CT scan correctly detected the primary tumor in55%(44of80)of patients with histologically proven cervical CUP. The sensitivity, specificity, and accuracyof18F-FDG PET/CT scans were91.6%,90.6%, and91.25%, respectively. The lung andhead/neck area were the two most commonly detected primary tumor sites (36%each). Thepositive predictive value was93.6%and negative predictive value was87.8%. Furthermore, in25%(20out of80) of patients,18F-FDG PET/CT detected extra-nodal distantmetastases (M stage) leading to a re-staging and possibly influencing subsequent treatmentplans.Cox hazard ratio regression analysis revealed a significant difference in overall survivalbetween patients presenting with extra-nodal metastases (M stage), with a hazard ratio of5.22at95%CI (1.820-11.433, P=0.001) higher than those without distant metastasis. Therewere no statistically significant associations between other factors and prognosis.ConclusionThe present study indicates that whole body18F-FDG PET/CT scan is a significant andvaluable tool in the identification of the primary tumor site in patients with CCUP.Furthermore, FDG PET/CT scans are of great value in the assessment of the extent of nodalinvolvement and in detecting the presence of extra-nodal metastases, further optimizing themanagement of these patients.