title: Occult primary tumors of the head and neck: lack of benefit from positron emission tomography imaging with 2-[F-18]fluoro-2-deoxy-D-glucose.
abstract: BACKGROUND
  Patients who present with squamous cell carcinoma metastatic to cervical lymph nodes and no clinically apparent primary site present a therapeutic dilemma. Positron emission tomography imaging with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG-PET) has been shown to be useful for the examination of known primary tumors. This study was undertaken to determine whether FDG-PET imaging improves detection of occult primary tumors in patients with metastatic squamous cell carcinoma in the lymph nodes of the head and neck.
  
  
  METHODS
  Thirteen patients with pathology proven cervical lymph node metastases from clinically occult primary squamous cell carcinomas were evaluated prospectively with FDG-PET, in addition to standard clinical and radiographic techniques, as part of their pretreatment diagnostic evaluation. Direct panendoscopy and biopsy were performed on all patients in an attempt to detect primary tumor sites and to characterize them histologically.
  
  
  RESULTS
  A primary squamous cell carcinoma was confirmed after panendoscopy and biopsy in 3 of the 13 patients. The site of the primary tumor was correctly identified with FDG-PET in only one of these three patients. The FDG-PET study suggested a primary tumor location where no tumor was found in 6 of 13 patients; for 5 other of the 13 patients, the FDG-PET results were negative and no primary was found. No primary tumor locations were identified by computed tomography, magnetic resonance imaging, or direct panendoscopy. FDG-PET imaging correctly detected the location of the primary tumor in 1 patient (8%) and provided apparent false-positive results for 6 (46%) of the 13 patients.
  
  
  CONCLUSIONS
  FDG-PET imaging did not significantly improve detection of unknown primary squamous cell carcinomas in patients with metastases to lymph nodes of the neck. A high percentage of results were apparent false-positive.
authors.affiliation: Department of Radiation Oncology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1030, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Greven
authors.forename: J W
authors.initials: JW
authors.lastname: Keyes
authors.forename: D W
authors.initials: DW
authors.lastname: Williams
authors.forename: W F
authors.initials: WF
authors.lastname: McGuirt
authors.forename: W T
authors.initials: WT
authors.lastname: Joyce
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000556:secondary*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D006801:Humans; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008297:Male; D009382:Neoplasms, Unknown Primary / Q000000981:diagnostic imaging* / Q000473:pathology; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed
chemical_list: D019788:Fluorodeoxyglucose F18