Antidotes are not data. We have no reason to believe from your story that your would not have got skin cancer if he had spent all his time in a cave. Or maybe he wouldn't have, because he would have died of something even worse at 45.
Science is trying to work this out, it is complex. We know that sun exposure both protects from and causes skin cancer depending on the study. This is a complex subject, the only thing I think I can safely say is don't get a sunburn.
The 2006 Report on indicators for occupational disease
highlights there was an increase in skin cancer claims per million
employees/persons over a six-year period to 2004. The report
says that given the long latency period associated with exposure
and the onset of skin cancer, it is also likely that compensation
claims greatly understate the real incidence of occupational
skin cancer6
.
Science is trying to work this out, it is complex. We know that sun exposure both protects from and causes skin cancer depending on the study. This is a complex subject, the only thing I think I can safely say is don't get a sunburn.