Role of 18F-FDG PET/CT in the detection of primary malignancy in patients with bone metastasis of unknown origin

Objective: The present study investigates the role of F-18-FDG PET/CT in the detection of primary malignancy in patients with bone metastasis of unknown primary origin (BMUO). Material and methods: This retrospective study considered histopathological examination findings or clinical follow-up data as the standard reference in the diagnosis of primary tumors, and results were compared with results of PET/CT scans. Results: The study included 100 patients with BMUO (74 males, 26 females, mean age 61 years). The primary origin was identified in 92 of the 100 patients. Adenocarcinoma was the most common histopathological subtype in patients in whom the primary origin of tumor was detected (65.2%). The most common primary tumor was lung carcinoma (n= 52) followed by prostate (n=13), breast (n-7), colon (n=4), gastric (n= 3), ovarian (n=2), renal cell (n=2), adrenal (n= I ), thyroid (n= 1), endometrial (n=1) and parotid (n= I) carcinoma, hepatobiliary cancers (n=2), leiomyosarcoma (n=2) and maxillary sinus tumor (n = I ). The numbers of patients in whom PET/CT showed true positive, true negative, false positive (FP) and false negative (FN) results were 72, 7, 8 and 13, respectively. The sensitivity, specificity, accuracy and detection rate of PET/CT in detecting the primary tumor were 84.7%, 46%, 79% and 72%, respectively. The overall survival was significantly lower in lung cancer group when compared to non-lung cancer group, whereas it was significantly higher in prostate cancer group than in non-prostate cancer group. Conclusions: PET/CT, as a non-invasive method, can be preferred as the first choice in the detection of primary tumor in patients with BMUO. (C) 2019 Sociedad Espanola de Medicina Nuclear e Imagen Molecular. Published by Elsevier Espana, S.L.U. All rights reserved.