Age-Related Physiological and Pathological Changes

– Susceptibility to Cancers

Cellular senescence may be critical early in life because it limits cell proliferation and helps suppress cancer. But as we get older, senescent cells might be harmful because changes in the genes they express might actually promote unregulated growth and tumor formation. Limited proliferation is the norm in the world of human cells. In some cases, however, a cell somehow escapes this control mechanism and goes on dividing, becoming, in the terms of cell biology, immortal. And because immortal cells eventually form tumors, this is one area in which aging research and cancer research intersect.

Telomere research is another territory where cancer and aging research merge. In immortal cancer cells, telomeres act abnormally—they no longer shrink with each cell division. Telomerase, which is not active in most adult cells except advanced cancer cells and germ cells, can enable cells to replace lost telomeric sequences and divide indefinitely. If a drug could be developed to block telomerase activity, it might aid in cancer treatment.

In addition, researchers have found defects in DNA repair in people with a genetic or familial susceptibility to cancer. If DNA repair processes decline with age while damage accumulates as scientists hypothesize, it could help explain why cancer is more common among older people.