The team at Johns Hopkins University, where the test was developed, say a commercial product is years away and they are working to fine tune their test -- many cancers were not found by the blood test alone. But their results are the first to demonstrate that it's possible to screen people for several types of cancer at once with a blood test. They tested about 10,000 women with no symptoms. Those who had a positive test then were given combination PET and CT scans to look for tumors. Out of the 10,000 women, the test turned up 26 cancers...