A few years ago researchers in California received widespread attention for showing that dogs can smell cancer on a human's breath. With 99 percent accuracy the canines could detect if a person had lung or breast cancer, beating the best figures from standard laboratory tests. Subsequent studies confirmed the results. Technology startups have hustled to build digital devices that can mimic the dogs' olfactory sense and reduce the need for biopsies and CAT scans. Metabolomx, a 12-person outfit in Mountain View, Calif., [is] bringing a cancer-sniffing device to market. The machine analyzes the breath and its volatile organic compounds, or VOCs-aerosolized molecules that, among other things, determine how something smells. Tumors produce their own VOCs, which pass into the bloodstream. The lungs create a bridge between the bloodstream and airways, so the breath exhaled by a patient will carry the VOC signatures of a tumor if one is present. It may seem surprising, but it's actually very straightforward," says Paul Rhodes, the co-founder and chief executive officer at Metabolomx. Dr. Peter Mazzone, a lung cancer expert at the Cleveland Clinic, recently published results from a trial he ran with an early version of the Metabolomx machine. He studied 229 people and found that the machine could detect lung cancer more than 80 percent of the time. Just as intriguing, the machine outdid the dogs by distinguishing between different forms of lung cancer with about 85 percent accuracy, giving the doctor insight into whether a patient had an aggressive case.