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. 2014 Feb;39(2):131-5.
doi: 10.1097/RLU.0000000000000304.

Prognostic relevance of (18)F-FDG PET/CT in carcinoma of unknown primary

Niklas Breuer  1 , Florian F Behrendt, Alexander Heinzel, Felix M Mottaghy, Moritz Palmowski, Frederik A Verburg
Affiliations

Prognostic relevance of (18)F-FDG PET/CT in carcinoma of unknown primary

Niklas Breuer et al. Clin Nucl Med. 2014 Feb.

Abstract

Objectives: The aim of this study was to assess whether F-FDG PET combined with x-ray CT (F-FDG PET/CT) findings have a prognostic impact in patients with carcinoma of unknown primary (CUP).

Patients and methods: Seventy patients with CUP who were referred for F-FDG PET/CT were included. F-FDG PET/CT results were checked against available histologic diagnosis and follow-up data. For each patient, the SUVmax of the lesion with maximum uptake was measured.

Results: In 26% of the patients, a primary tumor was identified. The follow-up period after F-FDG PET/CT scan ranged between 3 and 45 months. Kaplan-Meier analysis revealed 1-year survival rates of 92% in the group without evidence of malignancy on F-FDG PET/CT, 78% in the group with locoregional disease, and 34% in the group with extensive disease on F-FDG PET/CT. Three-year survival rates in these groups were 73%, 71%, and 23%, respectively (P = 0.001). There was no significant survival difference between patients with regionally confined disease without identification of the primary tumor and those in whom the primary tumor was identified on F-FDG PET/CT (P = 0.25). This was also the case for patients with extensive disease (P = 0.26). The SUVmax of the lesion with maximum uptake was not significantly related to survival (P = 0.56).

Conclusions: F-FDG PET/CT is a helpful tool for the identification of the primary tumor in patients with CUP; it is also able to provide an accurate assessment of prognosis based on the extent of the disease without the need for identification of the primary tumor.

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