Ask HN: How do we shift to preventative medicine?

My grandfather, who is in otherwise great health, recently got diagnosed with late stage cancer of the kidneys. How feasible would it be to build an open source suite of diagnostic programs that people can use to build longer term, longitudinal health system? The idea is that by building transparent, open source diagnostic models and looping it into a platform where you can track your health data, we could build a preventative system. Am I being completely irrational, or missing something?