RESUMEN
OBJECTIVE: Carcinoma of unknown primary (CUP) is inability to detect primary tumor despite all imaging methods with a biopsy-proven tumor metastasis. In the present study, we aimed to investigate the diagnostic and prognostic value of F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) in patients with CUP. METHODS: The patients with a diagnosis of CUP between November 2009 and January 2020 were evaluated retrospectively. A total of 155 patients (96 men and 59 women) were included in the study. Survival rates of the patients were evaluated by Kaplan-Meier and log-rank statistical analysis. RESULTS: The correctly determined primary tumor by F-18 FDG PET/CT was found in 64 patients (41%) (true positive). F-18 FDG PET CT results were negative (false negative) in determining primary tumor localization in 14 (9%) patients whose had local disease. Of the 155 patients, 66 (42.5%) had true-negative results and 11 (7%) had false-positive results. The sensitivity of 82%, specificity of 86%, and accuracy of 84% were calculated. The SUVmax value of the malignant lesion was on average 8.9 (range 3.6-26.1). Kaplan-Meier analysis revealed that the 1-year survival rates were 37.3% in regional disease and 16% in extensive disease (log-rank test, p=0.021). CONCLUSION: F-18 FDG PET/CT is a useful method in the detection of primary tumor in patients with CUP. F-18 FDG PET/CT can be helpful the evaluation of the prognosis by showing the extent of the disease.
RESUMEN
Objectives: The aim of the study was to evaluate the utility of 18fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in the diagnosis, staging, restaging, and treatment response of childhood malignancies. Methods: This study included 52 patients (32 boys, 20 girls) who were referred to our clinic between November 2008 and December 2018 with the diagnosis of malignancy. The patients were evaluated retrospectively. Median age of the patients was 13 years (range 2-17). 18F-FDG was given to the patients intravenously, and time of flight with PET/16 slice CT was performed 1 hour thereafter. The lowest dose was 2 mCi (74 MBq) and the highest dose was 10 mCi (370 MBq). Fasting blood sugars of all patients were found below 200 mg/dL (11.1 mmol/L). Results: 18F-FDG PET/CT was performed to evaluate the response to treatment in 38 of 52 children, staging in 11 patients (staging and evaluation of the response to treatment in nine of them), restaging in 2 patients, restaging, and evaluation of the response to treatment in 1 patient. 18F-FDG PET/CT examination was reported as normal in 13 patients (5 girls, 8 boys). The pathological 18F-FDG uptake was detected in 39 patients (14 girls, 25 boys), which indicated metastasis and/or recurrence of the primary disease. Total number of deaths was 30 (13 girls, 17 boys). Conclusion: 18F-FDG PET/CT has a significant role for staging, restaging, treatment response, and detection of metastatic disease but it is limited for the early diagnosis of childhood cancers.