Here, Thomas Seyfried can explain this much better than I ever could: https://www.youtube.com/watch?v=KusaU2taxow
I think once we know where cancer comes from we can be much more effective at preventing it in the first place (proper diet) and treating it after the fact. With the current progress I think at some point we should be able to prevent pretty much close to all deaths from cancer.
Obviously, people will always be dying of something so preventing a cancer will only mean we will have other challenges to face.