Circulating tumor cells (CTCs) detected by triple-marker EpCAM, CK19, and hMAM RT-PCR and their relation to clinical outcome in metastatic breast cancer patients

Abstract

In order to investigate the prognostic value of circulating tumor cells (CTCs) in patients with metastatic breast cancer (MBC), the blood cells from 98 MBC patients and 60 controls were evaluated by RT-PCR to detect the presence of markers EpCAM, CK19, and hMAM. Peripheral blood was obtained from all patients with MBC before any systemic therapy. Immunofluorescence staining experiment was conducted on CTCs samples from 10 patients to investigate the coexpression of EpCAM, CK19, and hMAM. In addition, analyses were carried out for their correlation with patients' clinicopathologic features. EpCAM+, CK19+, and hMAM+ cells were detected in 50 (51.0 %), 43 (43.9 %), and 68 (69.4 %) of the 98 patients, respectively. Triple-marker-positive CTCs were detected in 86 of 98 (87.8 %) patients with a significantly higher rate than the control group. Among the 98 patients, 12 (12.2 %) patients were negative for three genes, 34 (34.7 %) positive for one gene, 29 (29.6 %) positive for any two genes, and 23 (23.5 %) positive for all three genes. Compared to single-marker detection, the triple combined marker detection exhibited significantly higher rate. Furthermore, the specificity of triple combined markers of serial test was 100 %. The expression of three genes was significantly correlated with lymph node metastasis, high histological grade, and high levels of serum CA153 and CEA. Double-immunofluorescence labeling confirmed the presence of following CTCs phenotypes: CK19+/hMAM+, CK19+/hMAM-, CK19-/hMAM+, CK19+/EpCAM+, CK19-/EpCAM+, CK19+/EpCAM-, hMAM+/EpCAM+, and hMAM+/EpCAM-. After 2 years of follow-up, the presence of CTCs with triple-marker positive in peripheral blood was an independent risk factor for reduced progression-free survival (PFS) and overall survival (OS), and the presence of CTCs before any chemotherapy predicts poor OS and PFS in patients with MBC.