Role of FDG PET/CT for detection of primary tumor in patients with extracervical metastases from carcinoma of unknown primary

Utility of 18F-FDG PET/CT in Treatment Strategies for Patients With Cancer of Unknown Primary: A Single-Center, Retrospective Change-in-Management Study

“…According to the definition of CUP, the study design, the clinical manifestations and indications, the detection rate of primary tumors in patients with CUP was 14.6% to 73%. 24 , 25 However, the estimated tumor detection rate for PET/CT was 39% for Soni et al 26 In a 155-patient cohort study by Bicakci, 27 18 F-FDG PET/CT correctly diagnosed the primary tumor with a 41% (true positive) detection rate. We included a cohort of more stringent requirements which benefited the performance of FDG PET/CT.…”

2-[18F]FDG-PET/CT in Cancer of Unknown Primary Tumor—A Retrospective Register-Based Cohort Study

“…In our study, a CUP patient is defined as having at least one pathologically verified metastasis with an unknown primary tumor at the time of biopsy. Other studies, however, define CUP differently and many require that a thorough diagnostic workup has been performed before defining patients as CUP patients [ 2 , 11 , 26 , 27 , 28 , 29 ]. This has the advantage of filtering out patients with metastases as first sign of malignancy for whom standard diagnostic imaging methods are sufficient for finding the primary tumor.…”

“…A few studies did not require a metastasis biopsy to confirm malignancy and included patients with a strong clinical suspicion of cancer as well [ 2 , 26 , 30 ]. This might improve early diagnosis in patients who would not otherwise be studied, which might lead to a better prognosis [ 17 ].…”

“…Other studies have found the median survival of CUP patients receiving a 2-[18F]FDG-PET/CT to be between 8.4 and 33 months. Unlike our study, these studies counted survival from time of 2-[18F]FDG-PET/CT, and not from the first hospital visit related to the disease [ 2 , 26 , 27 , 32 ]. None of these studies compared survival between CUP patients with a CT and CUP patients with a 2-[18F]FDG-PET/CT though, and our literature search indicated a general lack of these types of studies.…”

“…Cancer of unknown primary tumor (CUP) accounts for about 3–5% of definitive cancer diagnoses [ 1 ] and is usually defined as cancer with a biopsy-proven metastasis, but without an identified primary tumor after a standard diagnostic workup [ 2 , 3 ]. Diagnosis of CUP usually includes clinical exams, blood samples, biopsies, computed tomography (CT) scans of the thorax and upper abdomen (new guidelines from 2022 also include the pelvic area [ 4 ]), and evaluation by a medical diagnostics team [ 5 , 6 ].…”