My love-hate relationship with age structure in modeling aging and cancer

The application of age structure, the temporal ordering of events in a life cycle, is a subtle matter: there are risks in neglecting it, but also in relying on it without regard to the underlying biology. In modeling aging, the risk of relying on age structure is that the biological chain of events that is supposed to lead to the timing of events remains unclear. On the other hand, neglecting age structure can lead to impossible results/hypotheses: Peto’s paradox and the proposed association between lifetime number of stem cell and lifetime cancer risk are examples. Ironically, if cancer is the result of the accumulation of cellular mutations, it is perhaps the only cause of death that seems to fit the classical theory that aging follows simply from age structure; ironically, because whether cancer can justly be called a “senescent” (i.e., resultant of the aging process) cause of death has been contested. Perhaps the idea of non-genetic instability in tumor progression can be of some help here?