The molecular detection of circulating tumor cells in bladder cancer using telomerase activity.

PURPOSE: The detection of circulating tumor cells and micrometastases may have important prognostic and therapeutic implications. We investigated telomerase activity as a molecular marker for detecting bladder carcinoma cells in blood.

MATERIALS AND METHODS: Peripheral blood mononuclear cells were isolated from whole blood using Ficoll/Hypaque. Immuno-magnetic beads labeled with an epithelial specific antibody were used to harvest epithelial cells from peripheral blood mononuclear cells. Telomerase activity was detected in this select population using the telomerase-polymerase chain reaction-enzyme-linked immunosorbent assay test based on the telomerase repeat amplification protocol method. The clinical applicability of this technique was explored by evaluating 30 patients with muscle invasive or metastatic bladder carcinoma and 17 healthy volunteers.

RESULTS: Telomerase expression was detected in 27 of the 30 patients (90%) with high grade, muscle invasive or metastatic bladder cancer but in none of the 17 healthy controls.

CONCLUSIONS: This test is a minimally invasive and specific approach for detecting circulating epithelial cells in patients with bladder cancer. This method may have great value for monitoring cancer progression.