The unexpected contribution of immunosenescence to the leveling off of cancer incidence and mortality in the oldest old

In this paper the hypothesis that some features of immuno senescence might impact on the levelling off of cancer incidence and mortality in the oldest old will be considered. In fact, the term immuno senescence suggests that a progressive loss of immune system (IS) function occurs with aging. However, the age-related modifications of the IS can be more properly acknowledged as a 'remodeling' characterized by profound structural changes, which modify the functional properties of IS. We suggest that the expansion with age of natural killer cells (NK) and of T cells which progressively acquire phenotypes intermediate between T lymphocytes and NK cells, together with the age-related changes in the production of inflammatory/anti-inflammatory cytokines, such as INF gamma and IL-4, might create an environment unfavorable for neoplastic growth in the oldest old. In this perspective, studies on immunosenescence likely provide insights on mechanisms responsible for the individual capacity to escape from the life-threatening consequences of cancer outgrowth. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.