Detection of circulating tumor cells in metastatic breast cancer patients

OBJECTIVE: The objective of this study was the detection of circulating tumor cells (CTCs) in metastatic breast cancer patients. METHODS: Since only small numbers of circulating tumor cells (CTCs) are found in peripheral blood, at first we performed immunomagnetic separation as a concentration method suitable for selecting circulating tumor cells in peripheral blood. This was followed by analysis of isolated cells with the aid of laser scanning cytometry (LSC). Twenty eight patients with metastatic breast cancer were enrolled in the study and the control group consisted of 19 clinically healthy women. Six milliliters of peripheral blood was drawn for the analyses, but only in two patients the blood has been drawn twice. Blood samples were taken when no chemotherapy was administered, but hormonal therapy has been allowed. RESULTS: The positivity for CTCs was found in 20 (50.0 %) patients with metastatic breast cancer patients, while in 6 (31.6 %) healthy controls false positive circulating epithelial-like cells were detected. Because we did not use CD45 staining, we could not distinguish these circulating epithelial-like cells from CTCs. In a majority of metastatic breast cancer patients we found a mixed population of HER-2 gene expressing CTCs. We found that HER2+ CTCs in high numbers are CK19 + CTCs, while almost all HER2-CTCs are CK19- CTCs. CONCLUSION: The described method was found promising for estimating HER2 status on CTCs from peripheral blood in metastatic breast cancer patients.