Yeah, cancer definitely isn't the "low hanging fruit". Hospital errors and infections would be much easier to address, though as this article shows, even that is nearly impossible.
Whenever I hear people say stuff like this I there is a huge part of me that wants to say: Science and magic are not the same thing, just because you can describe something does not mean you can actually do it. I realize it's not productive, but people seem to confuse sci-fi physics and medicine with actual physics and medicine.
The simplest explanation I have come up with goes something like this. Cancer is you, the only thing that cancer describes is the breakdown of the billion year contract that enabled Multicellular organism to exist in the first place. There is no single way to tell cancer from non cancer and just as importantly almost cancer cells from normal healthy cells. You can literally have 2 different cancers at the same time that are closer to you genetically than each other. Out of something like 10^(10^10) viable forms of cancer, a few themes are vastly more common, but the edge cases are effectively endless.
PS: A billion years from now we might not find a way to travel faster than light because it might not be possible. It might not seem like it, but I am not convinced it's possible cure all possible forms of cancer in a human body. However, people with cancer are serving far longer after all this research than they where 40 years ago and continuing down this path hopefully we can transform cancer from one of the more common and nasty ways to die to something as rare as lighting strikes.
There's even more money spent on fighting idiocy, but despite the evident failure in your case I don't think that teachers have conspired in order to try and guarantee a future salary.