Role of whole body positron emission tomography/computed tomography scan with 18F-fluorodeoxyglucose in patients with biopsy proven tumor metastases from unknown primary site.
OBJECTIVE
The aim of this study was to evaluate the role of whole body PET/CT scan with (18)F-fluorodeoxyglucose (FDG) in the detection of the primary tumor in patients with metastatic cancer from unknown primary origin (CUP syndrome).


METHODS
Sixty-eight consecutive patients, with CUP syndrome (39 lymph nodes, 29 visceral biopsy proven tumor metastases), underwent a whole-body FDG-PET/CT study. All enrolled patients were unsuccessfully studied, within the previous month, with physical examination, laboratory tests and conventional diagnostic procedures. All the pathological findings identified at PET/CT scan and suspected for primaries, were further investigated. After PET study, the minimum follow-up period for the inclusion in the studied population was 3 months.


RESULTS
The primary tumor site was correctly identified by FDG-PET/CT in 24 patients (24/68, 35.3%): lung (n=9), rino/oro-pharynx (n=6), pancreas (n=5), colon (n=2), uterus (n=2). In 5 cases, FDG-PET scan did not identify a primary pathological focus, which was subsequently detected by other diagnostic methods within 3 months. In 39 patients (39/68, 57.4%), the primary tumor site was not localized. However, in 9 of them, FDG-PET/CT scan identified further unexpected metastases, modifying the stage of disease. Overall, the following oncological treatment was influenced by the PET scan, in a total of 33 patients (33/68, 48.5%).


CONCLUSIONS
Our data strongly support the diagnostic contribution of whole body FDG-PET/CT scan in the evaluation of patients with CUP syndrome and suggest its use in an early phase of the diagnostic iter to optimize patient management.
University Nuclear Medicine Service, ASO S. Giovanni Battista, Turin, Italy.
E
E
Pelosi
M
M
Pennone
D
D
Deandreis
A
A
Douroukas
M
M
Mancini
G
G
Bisi
D000328:Adult; D000368:Aged; D001706:Biopsy / Q000706:statistics & numerical data; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009382:Neoplasms, Unknown Primary / Q000175:diagnosis* / Q000453:epidemiology*; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000706:statistics & numerical data; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D051598:Whole Body Imaging / Q000706:statistics & numerical data*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18