title: The role of 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography in the management of patients with carcinoma of unknown primary.
abstract: OBJECTIVE
  Carcinoma of unknown primary is one of the ten most frequent cancers worldwide. Its median survival time is less than 10 months. Detecting primary tumour locations and/or occult metastatic lesions may inform definitive treatment and improve patients' prognosis. We aimed to determine: (1) the sensitivity, specificity and accuracy of (18)F-fluoro-2-deoxyglucose positron emission tomography/computed tomography; (2) its detection rate of primary tumour locations and occult metastases and (3) factors associated with improved survival times.
  
  
  METHODS
  We retrospectively reviewed all cases in the West of Scotland for the period 1 December 2007 to 31 May 2011 that met all our selection criteria: (1) diagnosis of carcinoma of unknown primary; (2) a thorough but negative 'work-up' and (3) (18)F-fluoro-2-deoxyglucose positron emission tomography/computed tomography report. Statistical methods included frequencies, Kaplan-Meier graphs and log-rank tests to compare survival times.
  
  
  RESULTS
  (18)F-fluoro-2-deoxyglucose positron emission tomography/computed tomography detected primary tumour sites in 19/51 (37.3%) and occult metastases in 28/51 (54.9%) of eligible patients. Its sensitivity, specificity and accuracy were 79.2%, 70.4% and 74.5%, respectively; 20/51 (39.2%) patients died during the study period with a median survival of 8.4 months (range 21.4, SD ± 6.2). The number of metastatic locations was strongly associated with survival (p = 0.002), but detection of a primary tumour site (p = 0.174) or histopathology (p = 0.301) was not.
  
  
  CONCLUSIONS
  (18)F-fluoro-2-deoxyglucose positron emission tomography/computed tomography detected occult metastatic sites in the majority and a primary cancer location in a substantial minority of patients. Our results were comparable with international literature and may indicate that (18)F-fluoro-2-deoxyglucose positron emission tomography/computed tomography have an early role to improve the accuracy of cancer staging and to optimise carcinoma of unknown primary management.
authors: Radiology Department, Glasgow Royal Infirmary, UK. patdeo75@yahoo.co.uk
authors: P
authors: P
authors: Deonarine
authors: S
authors: S
authors: Han
authors: F W
authors: FW
authors: Poon
authors: C
authors: C
authors: de Wet
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000401:mortality / Q000556:secondary*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000401:mortality / Q000556:secondary*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009382:Neoplasms, Unknown Primary / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology; D049268:Positron-Emission Tomography; D011379:Prognosis; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012606:Scotland / Q000453:epidemiology; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18fdg petct; Cancer of unknown primary (CUP)