How to Spot Circulating Tumor Cells
Cancer cells that have broken away from the main tumor can spread the disease. Now scientists are developing better ways to find them.
One way that cancer spreads through the body is through circulating tumor cells. These are cancer cells that have broken away from the main tumor and begun to circulate in the blood. A new tumor can form if they become embedded elsewhere in the body and begin to grow.
So spotting circulating tumor cells is an important goal in the treatment of cancer.
Here’s the problem though. Circulating tumor cells are extremely difficult to find. In a single millilitre of blood there are usually several billion red blood cells, several million white blood cells but fewer than ten circulating tumor cells.
And there is the only one way to find them. The cells can be made to look different from normal blood cells. So you need a highly trained cell biologist with a microscope and plenty of time. The words needle and haystack don’t do this task justice.
Various groups are looking for better ways to find circulating tumor cells and their efforts fall essentially into two categories. The first is biochemical: trapping the cells using antibodies that bond to them. The second is mechanical: filtering them out.