Chapter 01 – Introduction
Increasing age is one of the strongest risk factors for cancer development. There is a marked increase in epithelial carcinomas from ages 40 to 80 years. Interestingly, the incidence of cancers levels off beyond age 80. The link between cancer and ageing is complex, and most of the fundamental questions remain unanswered. In some instances, such as cellular senescence or telomere shortening, strategies that protect us from cancer may increase our rate of ageing. However, cancer and ageing also seem to share common aetiologies, such as genomic instability and reduced rate of autophagy.
We still do not know whether DNA damage is the ultimate stimulus to both cancer and ageing. Another explanatory model views cancer and ageing as stem cell diseases, where cancer represents the effect of growth promoting mutations within a given stem cell while ageing represents the natural exhaustion and depletion of the stem and progenitor pool.
A common misconception among the general population and some doctors is that all cancers grow slowly in older patients. This is true for some cancers, such as certain types of breast cancer and lung cancer, but the opposite is true for other cancers such as acute leukaemias, brain tumours, and ovarian cancer, which may be more aggressive in older patients.