An ultrasensitive tumor enriched flow-cytometric assay for detection of isolated tumor cells in bone marrow of patients with breast cancer

Background An ultrasensitive tumor enriched flow-cytometric assay was used to determine its feasibility in detection of isolated tumor cells (ITC) in bone marrow (BM) of patients with breast cancer. Methods Epithelial cells were removed by magnetic microbeads conjugated with an anti-cytokeratin 7/8 monoclonal antibody to enrich tumor cells in BM samples. A specific gate for MCF-7 breast cancer cells (gateMCF-7 cells) was also taken into consideration in addition to a gate including all enriched BM cells (gateenriched BM cells) in flow-cytometric analysis to enhance the specificity of the method. Results Nineteen patients with stage I/II were evaluated. Ten patients (53%) were found to have cytokeratin positive (CK+) cells according to the gateenriched BM cells whereas 6 patients (32%) had CK+ cells when the gateMCF-7 cells was taken into account. Conclusions New strategies in nonmorphological ultrasensitive techniques might be useful to categorize patients with ITCs having different tumor morphology and characteristics