Diagnostic efficiency of PET/CT in patients with cancer of unknown primary with brain metastasis as initial manifestation and its impact on overall survival

Abstract

Background Carcinoma of unknown primary (CUP) is a diagnostic and therapeutic challenge; correct diagnostic approach results in better outcomes in patients with brain metastasis. Whole body 18 F-FDG PET/CT is a helpful modality to detect the origin of primary tumor and assess metastasis in the rest of the body. We assessed the value of PET/CT in detection of unknown primary in 39 patients with brain metastases as initial presentation and detected its impact on their overall survival. Results PET/CT could correctly detected the primary tumor in 49% of patients which occurred mainly in the lung, 63% of patients had additional extracerebral metastatic sites mostly in lymph nodes. Specificity, sensitivity, and accuracy of PET/CT in CUP patients were 95%, 79%, and 87%, respectively. No significant difference was noticed in estimated overall survival time between patients with an identified primary tumor and patients with unidentified primary tumor. Conclusion PET–CT was a helpful non-invasive imaging modality in detecting primary in CUP patients with metastatic brain lesion. It helped in the diagnosis of unexpected extracerebral metastatic lesions. However, the identification of the primary tumor by PET/CT has no significant prognostic effect on patient overall survival.

Diagnostic accuracy of f18-fluorodeoxyglucose positron emission tomography-computed tomography in the evaluation of carcinoma of unknown primary: A single-center study

“…15 The overall diagnostic accuracy was found to be 85.7% in this study which is consistent with the published data showing diagnostic accuracy within the range of 83-87%. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In our study, the sensitivity was calculated as 94%, specificity as 40%, PPV 89.2%, and the NPV 57.1%.…”

“…The term refers to a clinical disorder that revolves around and represents a diversified metastatic tumor Diagnostic accuracy of f18-fluorodeoxyglucose positron emission tomography-computed tomography in the evaluation of carcinoma of unknown primary: A single-center study group for whom the diagnostic investigations are unable to pinpoint the primary site of the tumor, comprising extensive radiological techniques, invasive endoscopic procedures, and histopathology, many which fail to diagnose the primary site. 1,2 CUP is one of the ten most commonly encountered diagnosis among the patients evaluated for metastatic cancers, estimating 3-5% of all malignancies. In the population of cancer-related mortality, CUP is considered as fourth most frequent reason.…”

The usefulness of [18F]FDG-PET/CT in detecting and managing cancers with unknown primary site depends on histological subtype

“…Our overall rate of tumor detection was 44%, which is within the range of 10%-75% reported in other studies 3,11,[14][15][16][17][18] . While CUP syndrome is a relatively common clinical entity, presentations and histologies are diverse 9,19,20 . Notably, consensus has not been reached as to whether CUP syndrome is simply a group of metastatic tumors with an undetected source, or a distinct entity with its own characteristics and behavior 17,21,22 .…”

What Does PET Imaging Bring to Neuro-Oncology in 2022? A Review

“…The main sites of other extracerebral metastases are in lymph nodes, especially mediastinal, hilar and retroperitoneal ones [ 57 , 58 ], and the lung was the most frequent primary tumor in patients with brain metastases [ 58 , 59 ]. Moreover, [ 18 F]FDG PET detected additional extracerebral metastatic sites in 42% to 63% of patients [ 57 , 58 , 59 , 60 ].…”