THE ROLE OF PET CT IN CANCER OF UNKNOWN PRIMARY Primeri Bilinmeyen Kanserlerde PET BT'nin Rolü

ABSTRACT Objective: This study aimed to investigate the diagnostic value of positron emission tomography/computed tomography (PET/CT) in detecting the primary focus and in suspicious foci in patients who underwent PET/ CT with a pre-diagnosis of carcinoma of unknown primary. Material and Methods: In this retrospective study, a total of 49 patients who underwent PET/CT scan with a prediagnosis of carcinoma of the unknown primary between 2015 and 2019, and whose clinical follow-up and histopathological data were available, were included. PET/CT study was performed in 20 (40%) patients after the metastatic lesion was detected as a result of pathology, and in 29 (60%) patients due to clinical findings and imaging methods and suspicion of malignancy. The histopathological and clinical evaluation of the patients before PET/CT and the primary surgery, histopathological examinations and clinical follow-ups after PET/CT were examined. The success of PET/CT in detecting primary lesions and evaluating suspicious lesions in metastatic cases was analyzed. Results: Seventeen (34.7%) of the patients were female and 32 (65.3%) were male. A primary malignant tumor was detected in 34 (85%) of 40 patients with PET/CT. Regional distribution in patients with primary cancer focus; 9 pancreases, 9 lungs, 4 livers, 3 urothelial, 2 thyroids, 1 vertebra, 1 breast, 1 ovary, 1 esophagus, 1 prostate, 1 iliac bone, 1 skin, 1 stomach and 1 colon. In the follow-up of 6 cases whose primary could not be determined; Cervical cancer was detected in 1, ovarian cancer in 1, and the primary focus could not be detected in the clinical follow-up of 4 metastatic patients. Conclusion: PET/CT is highly successful in detecting cancers whose primary is unknown. Therefore, PET/CT is a diagnostic imaging method for the detection of the primary in cancer patients whose primary is unknown.