Detection of circulating tumor cells in peripheral blood of patients with metastatic breast cancer: a validation study of the CellSearch system.
OBJECTIVE
The CellSearch system (Veridex, Warren, NJ) is designed to enrich and enumerate circulating tumor cells (CTCs) from peripheral blood. Here, we validated the analytic performance of this system for clinical use in patients with metastatic breast cancer.


METHODS
This prospective multicenter study conducted at three independent laboratories involved samples from 92 patients with metastatic breast cancer. Intra- and inter-assay variability using controls containing defined numbers of cells (average, 50 and 1,000, respectively), cell stability based on varying storage and shipment conditions, recovery precision from samples spiked with 4 to 12 tumor cells, inter-instrument variability, and positivity of samples from metastatic breast cancer patients were tested.


RESULTS
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.


CONCLUSIONS
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.
Riethdorf
Sabine
S
Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Fritsche
Herbert
H
Müller
Volkmar
V
Rau
Thomas
T
Schindlbeck
Christian
C
Rack
Brigitte
B
Janni
Wolfgang
W
Coith
Cornelia
C
Beck
Katrin
K
Jänicke
Fritz
F
Jackson
Summer
S
Gornet
Terrie
T
Cristofanilli
Massimo
M
Pantel
Klaus
K
D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology*; D018929:Cell Culture Techniques / Q000295:instrumentation* / Q000379:methods*; D002478:Cells, Cultured; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D015337:Multicenter Studies as Topic; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D013696:Temperature; D013997:Time Factors