What if you could detect cancer at its earliest stages – before there are any symptoms that would send you to a doctor? What if such a diagnostic tool existed and it was low-cost, minimally invasive and easy to use? The impact would be huge.Northwestern University professor of bioengineering and biophotonics Vadim Backman is closing in on this goal. By the end of 2017 he expects that the first of a series of cancer pre-screening tests will be available for use by physicians.