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.