Neoplastic Growth Through the Human Life Span

Abstract

The predominant view in the scientific literature concerning the incidence of cancers throughout the human life span is that of an eschatological process with a linear increase in the incidence favored by aging of the organism. This is considered The Dogma and, with rare exceptions, another more realistic view of the problem is not accepted. The idea of a cancer-aging relationship is so ingrained that most authors describe only arguments favoring the idea and avoid finding other explanations that would go against the dogma. Cancers are different diseases that start and evolve each in its own manner, and trigger variable responses from the organism depending upon the neoplastic process under way and upon the physiopathology of the organism. The incidence of the different cancers is spread throughout the human life span, with regional differences for each cancer; for many cancers the incidence is increasing at younger ages. More than half the cancers become clinically manifest during the second half of the human life span and their frequency increases with age, but their natural history starts way back at earlier ages. The data suggest that the late manifestation is the result of the accumulation of events through time rather than of aging. Interestingly, late in the human life span the incidence of neoplastic disease declines. Is this due to the cohort of late survivals naturally resistant to the development of neoplastic processes, or to the characteristics of the last “window” of the human life span? The evolution of neoplastic disease is the result of pre- and postnatal aggressions suffered by the organism, genetic predisposition, and developmental changes that evolve continuously from the beginning to the end of the human life span. The identification of the causes of the different cancers through the human life span will help to understand both neoplastic disease and the changes occurring through the human life span leading to aging.