European Journal of Molecular & Clinical Medicine

Carcinoma of unknown primary syndrome (CUPS) is labelled when even after the extensive
work up in form history, physical examination, laboratory parameters, computed tomography
scan and various forms of imaging, the primary site is not identified in a biopsy -proven
malignancy.[1]
Carcinoma of unknown primary syndrome (CUPS) represents 0.5-9% of the patients with
malignant tumors and only 20-27% of primary sites are identified before
death.[2]Identification of the primary is important from the therapeutic and prognostic point of
view. Inability to located the primary site in CUPS leads to suboptimal cancer therapy which
have to a negative impact on the survival. Some studies have reported that although the
median survival time of patients with CUPS is less than 1 year, if the primary site is
identified and cancer directed therapy started accordingly, the chances of survival can be
increased.[3,4]However, a large number of primary tumors remains undetected approximately
40% even after a detailed evaluation.[1]Positron-emission tomography (PET) with 18Ffluorodeoxyglucose
(FDG) or PET combined with computed tomography (PET/CT) is
recommended in the diagnostic work up of patients with CUP.[5]The rate of detection of the
primary site varies; 24.5-41% for the FDG-PET. [6]and 22-73% with the FDG-PET/CT [7]The
efficacy of PET or PET/CT for the detection of primary sites in patients with CUP remains to
be determined especially in developing countries like India where there are limited resources
and high rate of false positivity due to infectious disease. The present retrospective study
aims to determine whether PET/CT had any additional advantage over the conventional
diagnostic modalities to identify the primary site.