Relevance of aging research for cancer.

Experimental studies of the survival curves of different species and of in vitro cell culture survival point to normal aging as a largely preprogrammed process. Reciprocal skin grafting among syngeneic young and old animals further demonstrates autonomous aging of this organ independent of the remainder of the body. This compartmentalization of change with age is also suggested when immune functions of various lymphoid organs are compared at different ages. Experimental studies also show that for some organs their susceptibility to certain carcinogens is diphasic, high early in life and high in senescence. A major question now is if preprogrammed age changes at the molecular level have steps in common with carcinogenetic processes.