Abstract
1923
Objectives The aim of this analysis is to describe the value of PET/CT in detecting primary site of malignancy in our patient population with histologically proven metastasis or with a high clinical suspicion of malignancy.
Methods 52 patients (24 male, 28 female; mean age: 55.1±14.3; age range: 21-82 years) who underwent PET/CT in our department for histologically proven metastasis or with a high clinical suspicion for malignancy, were included in the study. The results of 18F-FDG PET/CT and clinical follow-up data were reviewed retrospectively. 18F-FDG PET/CT results were compared with histologically analysis and/or clinical follow-up data. Patients were evaluated in two groups: 29 with histologically proven metastasis (group 1) and 23 with clinical suspicion of malignancy (group 2).
Results Primary site of malignancy was correctly identified by 18F-FDG PET/CT in 16 patients (16/52, 30.7%). Lung was the most common detected site (9/16). Twelve of 16 patients (75%) were in group 1 and 4 were in group 2. In 3 patients, the focus which was determined by PET/CT interpreted as benign histopathologically. In the remaining patients (33/52; 63.4%) the primary tumor site was not localized by PET/CT. However, in 5 of them PET/CT scan determined additional metastatic focus. Regarding the whole patient population, sensitivity and specificity of 18F-FDG PET/CT for detecting primary site were calculated 100% and 91%, respectively. Regarding the patients groups, the sensitivity and specificity of 18F-FDG PET/CT for group 1 and group 2 were calculated 100% and 88%; 100% and 94%, respectively.
Conclusions PET/CT is a useful method in detecting primary tumors and/or other focus in patients with unknown primary tumors. PET/CT might contribute to appropriate staging and to choose correct treatment approach in this patient group. However false positive results should be considered and histopathological confirmation should be done