Epithelial cell adhesion molecule (EpCAM)-based enumeration of circulating tumor cells (CTCs) has a prognostic value in solid tumors such as advanced breast, colon and prostate cancers. However, poor sensitivity has been reported in non-small-cell lung cancer (NSCLC). We have developed a microcavity array (MCA) system integrated with a microfluidic device for recovery and enumeration of CTsC, regardless of EpCAM expression level. This system can isolate tumor cells on the basis of differences in size and deformability between tumor and hematologic cells.Methods
Paired peripheral blood samples were collected from metastatic lung cancer patients. CTCs were enumerated by EpCAM-based immunomagnetic capture (CellSearch, Veridex) and by the MCA system. In the MCA system, trapped cells were stained with Hoechst 33342, FITC-labeled anti-pan cytokeratin antibodies and PE-labeled anti-CD45 antibodies for subsequent imaging analysis. CTCs were defined as cells with round to oval morphology, a visible nucleus, positive staining for pan-cytokeratin and negative staining for CD45. We evaluated the sensitivity of the MCA system for detecting CTCs in lung cancer patients compared with the CellSearch system.Results
Twenty-two metastatic NSCLC patients and 13 small-cell-lung cancer (SCLC) patients were enrolled into this study between April 2011 and January 2012. CTCs were detected using the MCA system in 17 of 22 NSCLC patients (count >1 per 7.5 ml) compared with 9 of 22 patients using CellSearch (P = 0.013). On the other hand, CTCs were detected using MCA in all 13 SCLC patients compared with just 9 of 13 patients using CellSearch (P = 0.012). More CTCs from NSCLC patients were detected by the MCA system (median 13, range 0–313 cells/7.5 ml) than by the CellSearch system (median 0, range 0–37 cells/7.5 ml) demonstrating statistical superiority (P = 0.002, Wilcoxon test).Conclusion
Our results suggest that the MCA system is potentially superior to the CellSearch system for detecting CTCs in lung cancer patients and further clinical development should be considered.