BACKGROUND: About 5-10% of cancer patients suffer from cancer of unknownprimary (CUP). Sophisticated diagnostic techniques have not improved diagnostic efficacy for these patients.The aim of our analysis was to evaluate serum levels of four tumor markers and to relate them to thehistology, number, and sites of metastases, the response to chemotherapy, and survival. MATERIAL/METHODS:Blood samples from 46 patients with CUP were assayed for CEA, CA 19-9, CA 15-3 and CA 125. Specific IMxtumor marker assays (Abbott) were used to measure tumor marker quantities. RESULTS: No significant differenceswere detected between the mean levels of all markers for the two histological types (adenocarcinoma vs.undifferentiated carcinoma). The comparison of tumor marker values in patients with one metastatic locationto those with two or more showed no significant differences. We found no differences in marker valuesbetween patients with disease sites in the thorax vs. those with abdominal metastases. The comparisonof marker negative, CEA positive and non-CEA positive patients failed to reveal significant differencesin response rate. The comparison of CEA positive and marker negative patients showed significant differencesin survival (log-rank, p=0.02). CONCLUSIONS: Our results suggest that patients with CUP have a nonspecificoverexpression of serum tumor markers and that routine use of these markers does not offer diagnosticassistance. Nevertheless, the pattern of expression of some biological markers, such as CEA, could haveprognostic significance for survival.

Keywords: Neoplasms, Unknown Primary, Tumor Markers, Biological