Detection of Circulating Tumor Cells in Peripheral Blood of Patients with Metastatic Breast Cancer: A Validation Study of the CellSearch System

Intra- and inter-assay precision for two sites were high: All eight positive controls analyzed in the same run and >95% of the run to run control values (n=299) were within the specified ranges. Recovery rate of spiked samples averaged between 80% and 82%. CTCs were detected in approximately 70% of metastatic breast cancer patients. CTC values of identical samples processed either immediately after blood drawing or after storage for 24, 48, or 72 h at room temperature or at 4 degrees C did not differ significantly. Shipment of samples had no influence on CTC values. When analyzing identical samples in different centers, inter-instrument accordance was high.

The CellSearch system enables the reliable detection of CTCs in blood and is suitable for the routine assessment of metastatic breast cancer patients in the clinical laboratory. Blood samples should be shipped at room temperature and CTC counts are stable for at least 72 h.