What cost youthfulness??

There seems to be an emerging trend that there is a cost to some genes that confer youthfulness/longevity. The cost is an increased risk of cancer.

If you stop to think about it, cancer cells can divide indefinitely. Thus, they act more like young cells than like old cells. As a result, a "youthful" cell may threaten the longevity of an organism. a key challenge of ageing research will be to find mechanisms for enhanced health and survival of organisms that keep cells under control.