The detection of circulating tumor cells in colorectal cancer patients by flow cytometry

Colorectal cancer (CRC) is one of the leading causes of mortality worldwide. In solid tumors, such as colorectal cancer, metastatic CRC is the most common form of cancer-causing death. Metastasis is associated with the presence of circulating tumor cells (CTCs) in the peripheral blood of cancer patients. In our study, CTCs were detected in blood samples of colorectal cancer patients, using with our modified convenient method for the strategies of CTC enrichment and detection. 7.5 mL peripheral blood samples were firstly collected and peripheral blood mononuclear cells (PBMCs) were isolated from the fresh blood samples by ficoll gradient separation. Next, the leukocytes in PBMCs were removed by magnetic microbeads conjugated with CD45 for a negative selection. Finally, the retained cells were labeled with anti-epithelial cell adhesion molecule (anti-EpCAM), cytokeratins (CK 8, CK 19 and the leukocyte-specific marker as anti-CD 45). All samples were analyzed by BD FACS Aria III flow cytometry. A total of 10 patients and 7 control group were included in this study. In our study, 2-13 between CTCs were detected in blood samples of colorectal cancer patients with CK19-based gating strategy, and no CTCs were detected in blood samples of healthy individuals. As a consequence, the real-time monitoring of the disease state and personal therapy development may use to be a tumor biomarker for the detection of CTCs from blood samples.