title: Clinical value of 18F-FDG PET-CT in detecting primary tumor for patients with carcinoma of unknown primary.
abstract: OBJECTIVE
  To investigate the clinical value in detecting occult primary tumors with (18)F-FDG PET-CT whole body imaging.
  
  
  METHODS
  120 patients with unknown primary origin were referred for (18)F-FDG PET-CT whole body imaging. All patients were performed (18)F-FDG PET-CT whole body scan. PET-CT images were interpreted by visual inspection and semi-quantitative analysis (standardized uptake value, SUV). Histopathological and formal clinical follow-up findings were used to assess the value of FDG PET-CT.
  
  
  RESULTS
  FDG PET-CT was able to detect the primary tumor in 54/120 patients (42.5%). The primary tumors were confirmed by histopathologic and formal clinical follow-up findings, and located in the head and neck (n=17), the lung (n=19), the breast (n=2), the esophagus (n=1), the stomach (n=2), the bile ducts (n=1), the pancreas (n=3), the co1on (n=3), the ovary (n=2), the prostate (n=l), others (n=3). FDG PET results were proved false positive in 9 patients (7.5%), which were located in the head and neck (n=3), the lung (n=1), the gastric (n=1), the colon (n=2), the ovary (n=1), the prostate (n=l). During the clinical follow-up of median 32 months (range, 2-45 months), primary tumor was found in only 5 patients of 60 cases unidentified by PET-CT (breast cancer, gastric cancer, co1on cancer, prostate cancer and urinary tumors, respectively). The sensitivity, specificity, and accuracy of (18)F-FDG PET-CT in the detection of the primary tumor site were 91.5%, 85.2%, and 88.3%, respectively.
  
  
  CONCLUSIONS
  (18)F-FDG PET-CT whole body imaging is both a noninvasive and a very sensitive tomographic whole-body imaging modality, allowing for the detection of a primary tumor and complete tumor staging in single examination, which can contribute substantially to selecting appropriate therapeutic methods and evaluating prognosis. Perhaps (18)F-FDG PET-CT whole body imaging should be used as a first-line imaging modality for patients with carcinoma of unknown primary rather than using it after other diagnostic procedures have failed to identify a primary tumor.
authors.affiliation: Medical College of Shandong University, Department of Radiation Oncology, Shandong Cancer Hospital, 44# Wenhua Xi Road, Jinan 250012, Shandong, China.
authors.forename: Anqin
authors.initials: A
authors.lastname: Han
authors.forename: Jie
authors.initials: J
authors.lastname: Xue
authors.forename: Man
authors.initials: M
authors.lastname: Hu
authors.forename: Jinsong
authors.initials: J
authors.lastname: Zheng
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology / Q000556:secondary*; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000473:pathology / Q000556:secondary; D004067:Digestive System Neoplasms / Q000175:diagnosis; D005260:Female; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000175:diagnosis; D006394:Hemangiosarcoma / Q000175:diagnosis / Q000473:pathology / Q000556:secondary; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D009382:Neoplasms, Unknown Primary / Q000175:diagnosis* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000175:diagnosis; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000175:diagnosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000175:diagnosis; D014057:Tomography, X-Ray Computed; D014571:Urologic Neoplasms / Q000175:diagnosis
chemical_list: D019788:Fluorodeoxyglucose F18