[Treatment of patients with cancer of unknown primary - possibilities and problems].

Cancer of unknown primary is a relatively common clinical entity that accounts for 3-5% of all invasive cancers. Clinical entities of this heterogeneous group of diseases can originate from different tissues of the body and be manifested as metastases in different organs. Clinical behavior can be favorable or more often unfavorable. Clinical work-up should be practical and effective while excessive delay can turn clinically treatable disease to untreatable state. Favorable clinicopathologic entities should be treated similarly to known equivalent tumors. Unfavorable clinicopathologic entities should receive doublet chemotherapy if possible. Currently there is no clear evidence for usefulness of routine molecular testing. Patients are recommended to be selected in clinical trials if available.