There are all sorts of theories out there.....because we all want answers. We all want to have a reason for why this has happened, so we can ensure that it does not get repeated.
If we did have the answers, there would be many who would try to discredit them.
We are all individuals.
If my cancer had to have a cause I would put it down to stress......years and years and years of being a workaholic and (in many cases) self-applied stress.
The fact is that I have had cancer.......now I live with that....the tragedy (for me) would be if I started to worry about it and not LIVE this life that I have.