Detection of circulating urothelial cancer cells in the blood using the CellSearch System.

Background: Circulating tumor cells (CTCs) have been shown to aid in the therapeutic management of patients. But, only a few attempts have been made at the detection of urothelial cancer cells in the blood. The purpose of this study was to test the hypothesis that CTCs are detected in patients with urothelial cancers using newly developed CellSearch Assay.

Methods: Firstly, the bladder cancer cell lines were used to evaluate the reagents for immunocytochemical detection. After, mixed with peripheral blood mononuclear cells (PBMCs) of healthy volunteers, bladder cancer cells were stained with antibodies then multiparameter flow cytometric analysis was performed for the identification of bladder cancer cells in the PBMCs. Secondary, recovery of known numbers of spiked bladder cancer cells from whole blood was examined using CellSearch Assay. Finally, blood samples from nonmetastatic and metastatic urothelial cancer patients were investigated for CTC detection using CellSearch Assay.

Results: 1: Flow cytometric analysis revealed that it is possible to identify bladder cancer cells in PBMCs. 2: Sensitivity examination for detection of urothelial cancer cells with CellSearch Assay: Single regression analysis of the spiked number of cells vs. the recovered number of cells yielded a good correlation in this experiment. 3: Urothelial cancer cells were detected in 8 of fourteen patients (57.1%) with distant metastasis. Despite, no patient with nonmetastatic urothelial cancers showed positive result for this assay.

Conclusion: This is the first report of attempt to detect circulating urothelial cancer cells in the peripheral blood of the patients with metastatic and nonmetastatic urothelial cancers by CellSearch Assay.