title: Is 18F-FDG PET/CT useful for imaging and management of patients with suspected occult recurrence of cancer?
abstract: Rising serum tumor markers may be associated with negative imaging in the presence of cancer. CT and (18)F-FDG PET may yield incongruent results in the assessment of tumor recurrence. The present study evaluates the incremental role of (18)F-FDG PET/CT for the diagnosis and management of cancer patients with increasing levels of tumor markers as the sole indicator of potential recurrence after initial successful treatment.
  
  
  METHODS
  Thirty-six cancer patients with increasing levels of tumor markers during follow-up and negative CT underwent (18)F-FDG PET/CT, which showed 111 sites of increased tracer uptake. PET/CT was compared with PET results on a site-based analysis for characterization of (18)F-FDG foci and on a patient-based analysis for diagnosis of recurrence. The clinical impact of PET/CT on further patient management was evaluated.
  
  
  RESULTS
  Thirty patients (83%) had recurrence in 85 malignant sites (77%). For the site-based analysis, PET had a sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 96%, 50%, 85%, 85%, and 82%, respectively, as compared with the performance indices of PET/CT of 100%, 89%, 97%, 97%, and 100%, respectively. There was a statistically significant difference between the specificity (P < 0.05) and accuracy (P < 0.001) of PET and PET/CT for precise characterization of suspected lesions. For the patient-based analysis, PET had a sensitivity, specificity, and accuracy of 93%, 50%, and 86%, respectively, as compared with PET/CT with values of 93%, 67%, and 89%, respectively (P = not significant). PET/CT was the single modality that directed further management and treatment planning in 12 patients (33%).
  
  
  CONCLUSIONS
  The results of this study indicate that PET/CT may improve the accuracy of occult cancer detection and further lead to management changes in patients with increasing levels of tumor markers as the sole suspicion of recurrent malignancy.
authors.affiliation: Department of Nuclear Medicine, Rambam Medical Center, Haifa 35254 , Israel. o_israel@rambam.health.gov.il
authors.forename: Ora
authors.initials: O
authors.lastname: Israel
authors.forename: Maya
authors.initials: M
authors.lastname: Mor
authors.forename: Luda
authors.initials: L
authors.lastname: Guralnik
authors.forename: Nirit
authors.initials: N
authors.lastname: Hermoni
authors.forename: Diana
authors.initials: D
authors.lastname: Gaitini
authors.forename: Rachel
authors.initials: R
authors.lastname: Bar-Shalom
authors.forename: Zohar
authors.initials: Z
authors.lastname: Keidar
authors.forename: Ron
authors.initials: R
authors.lastname: Epelbaum
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000379:methods*; D014055:Tomography, Emission-Computed / Q000379:methods*
chemical_list: D015415:Biomarkers; D019788:Fluorodeoxyglucose F18