Circulating tumour cells in breast cancer: Prognostic indicators, metastatic intermediates, or irrelevant bystanders? (Review).

Circulating tumour cells (CTCs) have been of considerable interest for many years. The rarity of these cells presents the main challenge associated with their analysis. Current detection methods use antibody and nucleic acid techniques and are sensitive for CTC detection but limited in their utility by the occurrence of false-positive results. Despite this, there are a number of clinical studies which show that the presence of CTCs is an important prognostic indicator, particularly in the metastatic setting. Current efforts to phenotype CTCs may provide a valuable insight into the metastatic process and may also allow the development of specific CTC-targeted treatment strategies in the future.