The case for liquid biopsy
Shed by tumors into the circulation, Circulating Tumor Cells (CTCs) offer a window into cancer biology. However, the capture of CTCs from blood is not easy as CTCs are relatively scarce, with concentrations as low as 1-10 CTCs/mL of whole blood, against a background of millions of white blood cells and billions of red blood cells.
Clinicians continue to rely on invasive tissue biopsies as a means to assess a patient’s disease and prescribe appropriate treatment regimens. Not only is this risky and expensive, it limits the understanding of disease.
When a surgeon perform a tissue biopsy the cancer cells are extracted from a single location in a single tumor. Cancer is known to be heterogeneous (mixture of distinct cell lineages or clones) so it is likely this does not provide a complete understanding of the patient’s disease. Furthermore, as a patient undergoes treatment, the opportunity to monitor cancer status and adjust treatment is not available.
Collecting tumor cells from circulation results in a more representative sample that can be collected frequently allowing for ongoing monitoring of the disease. The potential of this is tremendous and the microfluidics technology finally allows CTCs to realize their full potential.