Just imagine if you could take a blood test each year, and this test would tell you that you had the start of a cancer or other chronic illness. Then imagine that you could take a course of medication that would nip this cancer or illness in the bud. The cancer would not even get chance to grow large enough to be seen on any scans.
What an amazing world it would be if we could eradicate the scourge of cancer, HIV, Lyme and other serious illnesses, but sadly, the current set up of the medical system does not allow for this type of radical thought process.