The promise of diagnosing conditions early is an exciting one. But there are fears among some health professionals that more screening might not be entirely helpful. In this programme, the BBC's Health Correspondent Matthew Hill finds out whether screening programmes can really help us live both better and longer lives. He asks whether diagnosing conditions decades before they might affect us causes more harm than good. He also examines what lessons from the past could tell us about the current surge in screening and considers some of the dilemmas it might present us with.