Primary cancers are rarely fatal even though one in four deaths in the United States can be attributed to cancer.
To help patients and physicians make treatment decisions, teams of researchers have been working on various methods to detect cancer's spread - via the bloodstream - before secondary tumors develop. Now, one team reports a nearly perfect method for separating breast cancer cells from blood. They describe their proof-of-concept device in a paper accepted for publication in Biomicrofluidics, a journal of the American Institute of Physics.
Detecting and separating circulating tumor cells (CTCs) is like finding the proverbial needle in a haystack: as few as one in a billion cells in a patient's bloodstream may be a CTC. Separation techniques vary widely, relying on differences in chemical, paramagnetic, or dielectric properties to distinguish CTCs from blood cells, or using mechanical sieves to cull the larger CTCs from the smaller blood cells. More recently, researchers have applied forces to fluid containing both blood cells and CTCs, using differences in inertia to sort cells. The technique, called "hydrodynamic sorting," is faster and easier than other sorting techniques. Like other mechanical techniques, it also allows researchers to collect viable cells after sorting them.