Cancer of Unknown Primary

Cancer of unknown primary (CUP) is defined as malignancy without known origin at the time of the initial diagnosis, thus representing a heterogeneous group of tumors with varying clinical features. Between 0.5% and 7% of all cancer patients are diagnosed with cancer of an unknown primary tumor (van de Wous et al. 2002). Detected primary revealed lung cancer most often, followed by oropharynx carcinoma, nasopharynx, breast, colorectal, and esophagus carcinoma (Delgado-Bolton et al. 2003). Overall the primary tumor in CUP patients is detected in less than 40% of the patients by conventional diagnostic procedures, frequently after having performed many examinations in all patients. Moreover, even with autopsy the primary could only be detected in approximately 80%. Hypothesized reasons are a metastatic phenotype with a small size of the primary due to involution during the course of disease or an extremely slow growth rate, but none of the biological hypotheses is confirmed by results from the literature (Van de Wouw et al. 2003).KeywordsPositron Emission TomographyPositron Emission Tomography FindingPositron Emission Tomography ExaminationUnknown Primary TumorTumor Detection RateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.