Systemic therapy for cancer of unknown primary

Background CUP is a metastasized oncologic disease with unknown primary. In Germany 2-4% of all newly diagnosed cases of cancer belong to this heterogeneous group. Especially patients with disseminate metastasized CUP have a poor prognosis. Aim This review summarizes the current standard of systemic therapy in cancer of unknown primary and presents possible future treatment concepts. Materials and methods The survey is based on a focused search in the database PubMed and on analyses of current guidelines and recommendations of scientific societies. Results Improvement of CUP therapy requires classification into prognostically favorable subsets in order to provide subgroup-specific treatment. If a subgroup cannot be identified, standard therapy is a platinum-based combination chemotherapy according to histology. Application of immune checkpoint inhibitors and further targeted therapies in cases of detected driver mutations appears promising, but are currently only the subject of ongoing studies. In previous clinical trials, entity-specific therapies based on presumed primary tumors after broad gene expression analysis did not improve survival compared to platinum-based combination standard chemotherapy. Conclusion In addition to the standard treatment, primary tumor-independent therapeutic approaches are also being investigated. These developments give hope that the prognosis will improve even for patients with advanced CUP.