Aging is generally considered to be the consequence of stem cell attrition caused by the activity of tumor suppressor pathways that censor potentially malignant clones by eliciting apoptosis or senescence. An important effector of aging is the cyclindependent kinase inhibitor p16INK4a, which is also a known suppressor of cancer. The expression of p16INK4a is very low or absent in young organisms but increases with advancing age. We recently showed that, unlike healthy cells, acute myeloid leukemia (AML) derived blasts show a down-regulation of p16INK4a mRNA with increasing age. Based on this observation we hypothesize that suppression of defense mechanisms which protect older cells against cellular and DNA damage might facilitate oncogenesis in older individuals.