Via the New York Times, the American Cancer Society is backing off of its screening push for Breast and Prostate Cancer because there is simply not a lot of evidence it does much good.
I think people fall into the prevention trap because in the back of their minds they think of death and disease in moral terms. If we lived right or did right by our fellow man then we could prevent these tragedies.
However, in fact there is very little we can do. In the long run of course, there is nothing we can do. Here and there we can push the back the tide, but it is quite hard and we run into diminishing returns very quickly.
There is enormous potential for pharmacological treatments to radically alter the human experience in coming centuries. But, without massive increases in our knowledge base, no amount of effort is going to extend human life very much.
There is a strong parallel here with economic productivity. There is an urge to equate productivity with hard work, however, in fact productivity has almost nothing to do with hard work. It has everything to do with the slow accumulation of knowledge.