Significance of positron emission tomography-computed tomography in CUP syndromes

Background In terms of targeted, preferably individualized therapy, CUP (cancer of unknown primary origin) syndromes continue to be a challenge, usually requiring complex as well as time- and cost-intensive diagnostics. Methods The present work based on the current literature provides an overview of the possibilities and limitations of hybrid imaging using positron emission tomography-computed tomography (PET-CT) or PET-magnetic resonance imaging (MRI) in the diagnosis of CUP syndromes. Against the background of clinical expertise, a critical assessment of the value of PET diagnostics in CUP patients is performed. Results and conclusion Although the literature data are heterogeneous and mainly based on retrospective studies, the additional diagnostic benefit of PET/CT or PET/MRI is sufficiently proven. Usually used as "last-line diagnostics" after unsuccessful conventional diagnostics, these can detect the primary tumor lesion in a relevant proportion of patients and often lead to changes in initial patient management.