I do not think anyone who understands anything about cellular biology, let alone does actual cancer research, ever claimed that "cure for cancer is 20-30 years away" -- or even possible in principle. Cures for specific cancers, sure -- and in fact a lot more cancers are curable today than 20 years ago. But one general "cure for cancer", if you think about it, makes no more sense than one general "fix for broken car". Cell division is a natural tendency of all living cells. All muticellular organisms continuously keep this tendency in check. When the checking mechanism fails, cells start diving. Cancer results. Since the number of ways cells can escape this continuous check is essentially infinite (well, not infinite, but far larger than the number of, say, infectious diseases), true "cure for cancer" would have to be nothing short of reversal of entropy. It's like asking "Why hasn't anyone invented THE way to fix cars?" -- which would fix any and all war and tear at once? It's magic. Which is not to say any worn-out car can not be restored -- with enough effort, it can, -- but it requires many different specialized procedures, never quite the same for any two old cars. Same with cancer.