Aging, nutrient signaling, hematopoietic senescence, and cancer.

It is well known that cancer is one of the main causes of mortality in the aged population. Recent studies suggest that oncogenic pathways, such as the insulin-like growth factor-1 (IGF-I), Ras, and Akt/PKB, can contribute to both aging and cancer not only by promoting growth and preventing apoptosis, but also by promoting DNA damage and genomic instability. Epidemiological studies suggest that the chronic, low-grade inflammation that accompanies aging also contributes to tissue damage and tumor progression. Coupled with the accumulation of senescent cells and declining immune function, this leads to the generation and survival of cancer cells, possibly explaining why advanced age is the primary risk factor for cancer.