Chapter 01 – Introduction
Almost all age-related changes lead to reduced organ function. However, the elderly population is characterised by a marked variability in the rate of functional deterioration, both between individuals and within individuals. Three different trajectories of ageing have been described:
- Ageing with pathology and disability
- Normal ageing with some disability
- Successful ageing with minimal disability
The heterogeneity of the ageing process has practical consequences for the assessment of older cancer patients: patients need individualised assessments to determine their biological age. Biological age is believed to reflect a person’s remaining life expectancy and functional reserves, and will influence treatment decisions and predict treatment tolerance. There is no simple way to assess biological age, and one of the best clinical tools available to date is the comprehensive geriatric assessment (described in chapter 3 of this book).
Traditionally, within gerontology and geriatrics, natural age-dependent changes in structure or function of organs have been distinguished from age-related pathologies. This distinction is perhaps less useful from a practical point of view. Furthermore, normal age-dependent changes are believed to be associated with the prevalence of age-related disease, and organ disease along with the ageing process will exert synergistic effects on each other.
Another important characteristic of organ function and age is the close relation between supply and demand: cardiac output and respiratory function at rest remain largely unchanged with increasing age, but marked age effects appear when the systems need to perform under stress, for example during surgery or chemotherapy treatment.
Within oncology, decreased organ function in older patients may complicate treatment. For example, impairments in renal, hepatic, and bone marrow function increase drug toxicity. However, dose adjustments are usually not straightforward because there is a lack of accurate measurements of function or reserve capacity. Comorbidities and polypharmacy may be associated with an increased risk of side effects and drug interactions. Again, because of the broad physiological variations seen among the elderly, valid generalisations are difficult to offer.