Detection of hematogenous micrometastasis in patients with transitional cell carcinoma

Purpose: Cytokeratin 20 (CK 20) is selectively expressed in urothelium, gas tric intestinal epithelium, in Merkel cells and in a variety of malignant n eoplasms. CK 20 RT-PCR assay has been extensively used to detect isolated c ancer cells in peripheral blood, lymph nodes and bone marrow samples of pat ients with colorectal carcinoma. Since CK-20 is also actively expressed in transitional cell carcinoma (TCC), we analyzed, whether CK 20 Reverse Trans criptase Polymerase Chain Reaction (RT-PCR) is suitable to detect residual tumor cells in patients with transitional cell carcinoma of the bladder and the upper urinary tract. Materials and Methods: Nested Reverse Transcriptase Polymerase Chain Reacti on assay was used to analyze CK 20 transcripts in peripheral venous blood s amples and tumor biopsies of 49 patients with transitional cell carcinoma. Blood samples of 22 healthy volunteers served as negative controls. Results: CK 20 mRNA was detectable in blood samples of 12 of 49 patients wi th TCC. All blood samples of the control group tested negative. The detecti on rate for CK 20 mRNA significantly correlated (p = 0.0019, Cochran-Armita ge Trend Test;) to the stage of disease and increased from 0% in stage pTa to 63% in stage pT4. Conclusions: These results suggest that CK 20 is a suitable marker for the detection of disseminated TCC cells in peripheral venous blood samples and may be helpful in the molecular staging of TCC patients. The prognostic rel evance has to be evaluated in further followup,