Carcinoma of unknown primary

Abstract

Carcinoma of unknown primary (CUP) represents the group of heterogeneous tumors, which can be defined as the presence of histologically proven metastatic disease and unidentified site of origin at the time of diagnosis in spite of comprehensive diagnostic workup (Pavlidis, Acta Oncol 46:592-601, 2007). CUP tumors are not infrequently encountered in oncologic practice. The incidence of CUP tumors in oncologic patients is 0.5-7% at the time of the initial diagnosis (Abbruzzese et al. J Clin Oncol 12:1272-80, 1994; Daugaard, Cancer Treat Rev 20:119-47, 1994) and its prevalence is between 3% and 15% (Abbruzzese et al. J Clin Oncol 13:2094-103, 1995). Frequent first settings for the metastatic lesions are lymph nodes (37%); of these, 31% are located in the head and neck region, which is the most common site for metastases of unknown origin (Lefebvre et al. Am J Surg 160:443-6, 1990; Scheidhauer et al. PET in clinical oncology, 2000, pp. 169-76). CUP tumors present metastatic dissemination patterns that are different from those observed in oncologic conditions with known primary tumors: (1) Short symptomatic prediagnostic interval exists before the clinical presentation; (2) CUP tumor becomes symptomatic at the time of metastatic disseminations; (3) the most frequent primary sites in patients with CUP tumors do not include the several most common primary tumors in the general population; (4) no specific metastatic location has been consistently associated with a specific primary tumor site.