Please, please, don't take this as "blasphemy", but rather a logic-based "hunch".
I've always had a theory (among many other hunches in my life).
The theory was based on observation.
I'd observed that often (NOT always) people prone to cancer are those who were full of vitality - while alive.
Now that I've read that cancer is often embronyic stem cells "gone wild", it sorta backs up my theory.
Because stem cells usually have a HEALING effect.
So I'm thinking that people (like myself) who have always been full of pain, without healing easily internally (i.e. never bouncing back from stress) have a LACK of stem cells, and instead may be prone to calcifications.
Whereas those who have ALOT of stem cells (and therefore full of vitality) are also more at risk of those same vital-cells going haywire, and thus developing into cancerous growths.