Abstract
Recent technical advances have led to an increased interest in the detection and molecular characterisation of circulating tumor cells (CTC). Evaluation of CTC carries great potential as a tool in cancer patient management and prognostication. Numerous clinical trials on early and metastatic cancer are employing CTC to evaluate the efficacy of systemic therapy. There is also an increasing interest in using CTC for detailed molecular and cellular characterization of both well-characterized and novel biomarkers. However, technical difficulties have limited the opportunity to deeply probe these rare events, particularly as they occur in a background of millions of normal cells. Better characterization of CTC should clearly lead to a better understanding of cancer progression, the effects of therapy, and the identification of novel therapeutic targets. CTC evaluation is expected to become more widely used in both clinical and research settings.