Esoteric Testing Guide

CellSearch™ Circulating Tumor Cell Assay

The Department of Laboratory Medicine is pleased to offer the Veridex CellSearch™ circulating tumor cell assay (mnemonic EPCS). This is a FDA-approved test to detect the presence of circulating breast cancer cells in the peripheral blood. Whole blood (7.5 ml) is collected into a special anticoagulant tube (CellSave®). The blood is treated with iron-coupled antibodies to epithelial cells, which are captured by magnetic separation. The separated cells are then stained with fluorescent antibodies directed against cytokeratin to identify tumor cells, and against CD45 to identify blood cells, and the cells are stained with a fluorescent stain (DAPI) that binds DNA to detect cell nuclei. The stained cells are injected into a chamber that is scanned by a laser. Images of fluorescently labeled cells are collected by a computer, and the images are then reviewed by a technologist to verify the presence of tumor cells and to count them.

The assay is capable of detecting a single tumor cell in a tube of blood. Published data indicate that the presence of 5 or more tumor cells per tube of blood is predictive of worse clinical outcome and/or treatment failure (see reference).

The assay is offered twice a week, on Mondays and Thursdays. Blood collected into CellSave® tubes is stable for 3 days. CellSave® tubes can be provided upon request. For additional information, please contact Reference Laboratory Services.

Reference: Cristofanilli, M., Hayes, D. F., Budd, G. T., Ellis, M. J., Stopeck, A., Reuben, J. M., Doyle, G. V., Matera, J., Allard, W. J., Miller, M. C., Fritsche, H. A., Hortobagyi, G. N., and Terstappen, L. W. (2005). Circulating tumor cells: a novel prognostic factor for newly diagnosed metastatic breast cancer. J. Clin. Oncol. 23, 1420-1430.

Last updated: 09/20/06