Circulating tumor cells: a window into cancer biology and metastasis

The presence of circulating tumor cells (CTCs) accompanies tumor invasion into the bloodstream. Detection, monitoring, and molecular analysis of these rare cancer cells shed into blood will provide a powerful and noninvasive approach for the detection of early disease, assessing prognosis and therapeutic response in established cancers, and targeting metastatic precursor cells. We review current and emerging technologies for CTC isolation, with a focus on capture efficiency, purity, and viability of CTCs, and their potential clinical applications.