EurekAlert shows one of many ongoing investigations into the biochemical roots of the relationship between aging and cancer: "Proteins which prevent cancer in humans by ensuring that cells don't divide if they have chromosomal damage have been shown to determine lifespan in the nematode worm C. elegans. ... checkpoint proteins, traditionally thought only to be functional in cells that divide, are also active in cells that no longer divide. The fact that the proteins appear to have dual functions opens a new way to study the connection between aging and cancer.
... variations in checkpoint proteins in humans may place some individuals at risk for cancer, but protect them against other age-associated diseases; or conversely, set a genetic course for a shorter life which would be free from cancer. ... We think there are many more checkpoint proteins - in worms, in complex animals, in humans. Some may be more attractive than others for developing therapies for cancer and aging."

Link: http://www.eurekalert.org/pub_releases/2006-06/bifa-plt052506.php