Clinical value of ¹⁸F-FDG PET/CT in cancer of unknown primary

Objective: To evaluate the clinical value of ¹⁸F-FDG PET/CT whole-body imaging in the management of cancer of unknown primary(CUP). Methods: From February 2015 to June 2016, 46 CUP patients were analyzed retrospectively in Taizhou People's Hospital. They underwent ¹⁸F-FDG PET/CT imaging to detect their primary tumors that had not been detected through routine examinations. Visual and semiquantitative analyses were then employed to analyze the PET/CT images. The results were assessed on the basis of the pathological results, comprehensive clinical diagnoses, and clinical follow-ups. Results: Of the 46 patients, 33 had primary tumors, which were detected through ¹⁸F-FDG PET/CT imaging and further confirmed by pathology or clinical follow-up. Meanwhile, the primary tumors in 13 patients were not characterized. The CUP detection rate of the ¹⁸F-FDG PET/CT was 71.7%(33/46). Of the 33 patients with detected CUPs, 3 had lymphoma, 2 had gastric cancer, 4 had esophageal cancer, 3 had oophoroma, 14 had lung cancer, 2 had liver cancer, 1 had urinary tract epithelial cancer, 2 had nasopharyngeal carcinoma, 1 had multiple myeloma, and 1 had colon cancer. The modes of tumor metastasis included lymphatic metastasis in 32 cases, bone metastasis in 20 cases, liver metastasis in 13 cases, lung metastasis in 9 cases, pleural and peritoneal metastasis in 5 cases, adrenal metastasis in 3 cases, brain metastasis in 4 cases, subcutaneous metastasis in 3 cases, and pericardium metastasis in 1 case. Conclusions: The ¹⁸F-FDG PET/CT outperforms ordinary routine examinations in terms of CUP detection. Thus, ¹⁸F-FDG PET/CT possesses significant importance to clinical management. (authors)