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Objective: Recently,immunocytochemistry and immunomagnetic enrich- ment have been used in detecting circulating tumor cells(CTC).This study was designed to investigate the sensitivity and specificity of modified , immunomagnetic enrichment of tumor cells in combination with fluo- rescent immunocytochemistry in detecting CTC in peripheral blood of the normal volunteers and the patients with metastatic breast cancer.In the meantime, to study the feasibility that evaluating the effect of chemotherapy in metastatic breast cancer by the number of CTC at an early stage.Methods: The sensitivity of this detection method was evaluated by sparking breast carcinoma cell line MCF-7 into normal peripheral bloo- d.Mononuclear cells were isolated from peripheral blood of 30 patients with metastatic breast cancer before and after one chemotherapy cycle, mean- while,10 blood samples of the normal volunteers were collected once. Epithelial cell adhesion molecule (EpiCAM) antibody (Ab),covalently bound to magnetic beads,was used to enrich CTC expressing EpiCAM antigen.CTC,indicated by positive staining of cytokeratin(CK)8/18 (green fluorescence),was detected by modified fluorescent immunocytochemistr- y,and confirmed by DAPI nuclear staining(blue fluorescence).The number of CTC were detected by IME-FICC.In the meantime, evaluateing curative effect of chemotherapy with metastatic breast cancer by WHO criterion.Results: The sensitivity of IME-FICC was so high that 1×107 tumor cell in 1 peripheral blood mononuclear cells could be detected. Positive rate of CTC was significantly higher in peripheral blood of patients with metastatic breast cancer than in peripheral blood of the normal volunteers (70%vs0, P<0.05), The specificity of this method was 100%.The presence of CTC was correlated positively with axillary lymph node status (P<0.05),and irrele- vant with other prognostic factors (P>0.05).Among thirty patients with metastatic breast cancer, the prevalence of the number of circulating tumor cells increased, unchanged and decreased after one chemotherapy cycle were 43.3%(n=13), 26.7%(n=8) and 30.0%(n=9), respectively. The preva- lence of PD, SD and PR of 30 patients with metastatic breast cancer by imaging were 50.0%(n=15), 26.7%(n=8) and 23.3% (n=7), respectively. There was no significant difference between two groups (χ2=0.125,P>0.05).Conclusion:IME-FICC is a time-saving,easily-performed,sensitive and specific method for detecting CTC in peripheral blood of patients with metastatic breast cancer.The presence of CTC in peripheral blood correlates positively with axillary lymph node status of patients with metastatic breast cancer.The effect of chemotherapy in metastatic breast cancer could be predicted 3 to 4 weeks earlier by using the number of circulating tumor cells compared to imaging method.
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