Circulating tumor cells: finding the needle in the haystack

Abstract

Localized and metastatic cancers give rise to circulating tumor cells (CTCs) which are detectable in the bloodstream. Recent studies have highlighted the prognostic significance of the presence and number of CTCs, particularly in patients with metastatic disease. Future studies are designed not only to detect CTCs, but also to characterize them. This review discusses current and developing methodologies for the isolation and characterization of CTCs as well as recent studies focusing on the clinical relevance of CTC detection and characterization.

Keywords: CTCs; Circulating tumor cells; cell capture and enumeration; detection technique; enrichment technique; immunomagnetic separation.

Figure 1

Identification of RANKL-shedding cells in SAOS-2 cells transfected with MT1-MMP using the ELISPOT assay. Each immunospot identifies single viable cells shedding RANKL.

Figure 2

Sensitivity of RT-PCR analysis to detect genes of interest in cultured prostate cancer cells spiked in blood. Peripheral blood of a healthy volunteer was spiked with different numbers of LNCaP prostate cancer cells transfected with wild-type MT1-MMP (LNCaP-MT1wt), and processed using the Cell-Search® Profile kit. PCR amplification products obtained after a two-cycle amplification process in EpCAM-positive fractions demonstrate the feasibility of molecular analysis for diffferent genes in samples enriched using the CellSearch® platform. Peripheral blood mononuclear cells (PBMC) of the same volunteer were used as control.