BACKGROUND: Cancer of unknown primary site (CUP syndrome) is a particular challenge in oncology which occurs in about 5-10% of cancer patients. Here, we investigated clinicopathological and prognostic factors in patients with CUP syndrome in a retrospective analysis. PATIENTS AND METHODS: 136 patients with CUP syndrome who were treated in our Department of Oncology and Hematology were analyzed over a period of 10 years. Clinical and histopathological characteristics, response to chemotherapy, survival and prognostic factors were investigated in a retrospective analysis. RESULTS: 83 of the patients (61%) received first-line chemotherapy, which induced an overall response rate of 19%. Altogether 37 different chemotherapy regimens were used. Median overall survival of all patients was 7.9 months. In multivariate Cox regression analysis, gender, Karnofsky performance status, treatment modality and extent of disease were identified as independent prognostic factors. CONCLUSIONS: Our analysis showed a poor prognosis for patients with CUP syndrome. The response rate to chemotherapy was low with no significant benefit for any of the investigated cytotoxic agents. Newer diagnostic and therapeutical approaches might contribute to an improvement of prognosis, and their value is currently investigated in prospective studies.
