Ahmmmmm - well, that depends.
See, cancer is a funny thing. Not like I am an MD or something, let alone an oncologist, but lets say I have an interest . Between exposure and heredity, lets say I am a bit more likely than most to come down with problems.
What happens is that for some reason, radiation, injury, an odd substance introduced into the system, maybe a virus, a cell goes funny. The DNA in it is changed, maybe, just a little.
Now, if the immune system is fairly strong, it may be that the body sees that funny cell and deals with it. Maybe. Maybe not. Or some other process in the body that we don’t understand yet deals with it…or not.
Lets say it doesn’t. The cell replicates itself. And those two replicate themselves, and so on. Fun with the powers of two. Two squared, two to the third… eventually you have a whole lot of those strange cells. And they are reproducing and reproducing and either taking nutrients and such that you need to do other things or spreading into other tissues ( metastasising) or displacing normal cells and screwing things up. The term ‘insidious’ could have been made for this…
Now, some of us have immune systems and whatever else going on such that these little nasties get dealt with early. You see these people who seem to live to 100 while smoking like chimneys, drinking like fish and so forth.
On the other hand, there’s those who die young of this and that. Leukemia, what have you - buddy of mine did some 20 years back. And he’d lived awfully clean all his life. Just happened that he got it.
You hear about the Human Genome project, analysing human DNA to see what does what? Well, that’s part of it, seeing what seems to confer resistance to such things and what seems to go hand in hand with susceptibility to cancer and this and that. They are working on it, studying and analysing and so on. But it’s far from a done deal. There is one hell of a lot to analyse, connections to be made and all that. And it’s likely that it’s not just one part of the DNA that causes a given thing, it’s a whole pattern over literally millions of segments in it. Tremendously complex pattern, like codebreaking but far more complicated.
More exposure probably gives more chances for those cells to go odd on ya, yes, taking precautions only makes sense; you may be one of those who are more likely to develop something grotesque. Makes sense to limit the chances, y’know?
hope that’s of use