This is a very complex question and one worth exploring I think. I've also been doing a bit of research into it and what I've found is that the incidence of some cancers is increasing for reasons that can't be explained by lifestyle deficiencies and an ageing population alone.
For example, its widely cited that incidence rates of testicular cancer have been growing globally, and while a number of causes may have partially contributed to this, the overall rate of increase remains unexplained
(see: http://aje.oxfordjournals.org/cgi/reprint/150/1/45.pdf.). There has also been a steady, dramatic and unexplained decrease in male fertility around the world over the last hundred years and the cause of this also remains unexplained (http://www.dailymail.co.uk/health/article-158463/Why-male-fertility-decline.html).
Are these issues linked? are potential carcinogens like electromagnetic radition, caffine, car exhausts and the pill to blame? who knows?
Personally, I don't believe in the link between stress and illness. I know a lot of people are and I'm very close to a few of them, but to me the idea that there is some kind of link between these things would mean that I had control over my body developing cancer at some point, and that I failed in that. However, I think it is an interesting idea.
In the 2 years before I was diagnosed I had a lot of things happen: my wife was diagnosed with cancer; my father was diagnosed with cancer and passed away; we had several other family deaths; we had major issues with extended family members; my first child was born; we moved house 5 times including moving cities; one of my cats was killed and my dog died. All the time I was working in a fairly demanding and stressful job. But I still don't think any of that made me get cancer.
Also, here's another interesting article I found that talks about global cancer rates:
http://www.who.int/mediacentre/news/releases/2003/pr27/en/
... View more