About 1 in 4 deaths in the United States are due to cancer, but primary tumors are rarely fatal. Instead, it's when tumors metastasize that cancer becomes so deadly. 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...