There's a widespread myth at work here: that there's a disease called cancer. Cancer is actually the end result of what are probably hundreds (thousands?) of different diseases. We have confused ourselves by giving them the same category name - it's like the old-style classification of infections as various "fevers." There are many, many ways that a cell can end up with (and maintain) the deranged growth profile that we think of as cancerous, and it's going to take a lot of different treatments to do anything about them.
A good read.