The specific things that are needed to 'mutate', for a successful cancer, are related to the cells reproductive process. While free-radicals (often introduced by all the stuff Leprauchan mentioned) increase chances, there's always an inherent chance that you will develop Cancerous traits in an any ordinary cell during reproduction. This is one of the barriers to making ourselves immortal - there is absolutely no way we can control such a fine process and the longer we live, the more likely it is that the wrong cell breaks in the right way to for a malignant tumour.

Yhorian

PS - To Valg: Thought I'd ask a quick favour. I'm a student of genetics myself, I was hooked in by Telomeres back when I was thinking of University and it's what brought me in the direction of Biochemistry. It's often something I attack drunken friends with late at night while they're vulnerable, filling them with horrible dreams of immortality.

What I wanted to ask was related to the recent developments in understanding Cancer stem cells (and the theory that mutated tissue stem cells are the root of 99% of malignant tumours). Since almost all of our Cancer treatments still focus on killing majority cells instead of focusing on the stem cells - it's a really interesting time to pick people brains on the direction it might go.

I would be happy to know any ideas or opinions you've got on the subject. It's shockingly hard to find anyone nearly as nerdy as me, pursuing practical genetics to this level :P I'm assuming of course you've been following it, if you want me to shoot you my email address let me know and I'll aim it at valg@fields.