Not necessarily, though I should think it raises the odds of it happening. Genetic variation, levels of health, other lifestyle factors and so on are all in the mix when it comes to disease susceptibility. For example, not every heavy smoker or asbestos worker will get lung cancer, though its incidence is high in both of these groups.
As for avoiding all dodgy cancer-causing chemicals? Pretty much no chance, I'd say - potential nasties are everywhere, from rain to food to medicines to the radon that naturally seeps out of rocks.
I guess it's about living as healthy as possible, avoiding what nasties we can and not worrying about what we can't change.
What does everyone else think?