Diagnosestellung eines „cancer of unknown primary“

With an incidence of 1–3% of all malignancies, cancer of unknown primary (CUP) remains a relevant tumor entity. It is defined by histologically or cytologically proven cancer with an unidentified primary tumor after standardized and extended diagnostic workup.

This paper summarizes the current clinical standard of diagnostic workup in CUP syndrome with respect to different localizations and manifestations.

This paper is based on a focused literature search of the PubMed database and an evaluation of current guidelines and recommendations.

The diagnostic workup in patients with metastases of unknown origin is driven on the one hand by the localization, on the other hand by the histology including immunohistochemistry. A defined basic workup is expanded by investigations driven by the individual history and symptoms. Recently, specific diagnostic algorithms have been defined for certain clinicopathological constellations. The diagnosis of CUP syndrome is established if a primary cannot be identified. Treatment is driven by the presence of favorable subgroups with specific recommendations—or not. In the unfavorable subgroup, empiric treatment is given.

The establishment of new specific diagnostic algorithms leads to a better definition of CUP syndrome. The choice of therapeutic options and the inclusion criteria for clinical trials are thus improved.