Urinary cytokeratin 20 as a marker for transitional cell carcinoma

To determine if detection of cytokeratin 20 (CK20) gene expression, by reverse transcriptase-polymerase chain reaction (RT-PCR) in urine from transitional cell carcinoma (TCC) patients, can provide a new noninvasive tool for the follow-up of patients with urothelial carcinoma of the bladder.

Urine was collected from 95 patients previously diagnosed as TCC during their follow-up, and from 27 healthy volunteers. All patients had a transurethal resection of tumor or biopsies obtained from 'suspicious' areas in the bladder. RNA was extracted from cells collected from the urine and RT-PCR was performed with specific primers for the amplification of cytokeratin 8, a general marker for epithelial cells, and of CK 20, a marker for TCC urothelium.

CK20 expression was detected in 86.7% of TCC patients, and only in 3.3% of healthy volunteers (specificity 96.7%). Strong correlation was found between tumor grade and expression of CK20 in urine. All grade III and IV tumors demonstrated positive CK20 expression (100% sensitivity), whereas the sensitivity for lower grades was between 71 and 80%. Among 11 patients with a previous biopsy-proven diagnosis of TCC and a current negative biopsy, in 9 patients CK20 expression was detected. Further follow-up of these patients for a period of 6 months revealed recurrence of TCC in 4 patients.

CK20 detection in urine cells is a simple, noninvasive method with a high potential to become the marker of choice for monitoring and follow-up of TCC patients. More information is needed regarding CK20 expression in nonmalignant urological disease, to evaluate its use for routine screening purposes.