Age

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Age

Age is a property or a state which is defined as how long something has existed. For biological entities one discriminates between biological (physiological) and chronological age.

Information about age plays an important role in clinical reasoning about cancer. Yet, different disciplines conceptualise age in different ways. Epidemiological descriptions capture age parameters on a population level, which consider risk factors and cancer incidence. Clinical domain focuses on classification of patients, assessment of diagnosis and prognosis, whereby age is used as an important parameter which complements clinical classificatory categories. On the other hand, biological parameters capture age by looking at the biological processes such as telomerase activity, while the related biological classifications of cancer rarely include explicitly age classifiers. Since an apparently similar tumour may exhibit quite distinct behavioural patterns across different age groups, clinical decisions about prognosis and therapy choice all depend on information about the age of patients. For example, breast cancer in young and elderly people are often considered as distinct, age-dependent classes [Anderson+Al:2009] [Jatoi+Al:2008]. Clinical and epidemiological studies report that the risk factors, tumour characteristics and clinical trial results significantly vary across age groups (Wang, et al., 2007). The association of age and cancer characteristics is known as age interaction. Here, the age-dependent differences are not only in magnitude, but, more importantly, information about age changes the evaluation and interpretation of what the risk factors, cancer traits and therapy responses are. Thus, the relation between age and cancer specification or classification is not just a quantitative one, but also includes a qualitative difference. Moreover, there are a few age-thresholds [Anderson+Al:2009] where the qualitative age interactions take place [Sojic].

In general terms, the age-dependent differences can be explained by the age-related physiological processes that drive an age-specific behaviour of the tumour [Thomas+Leonard:2009]. On the other hand, a molecular characterisation of cancer aims at capturing typical molecular features of cancer subtypes whereby the age differences are often intentionally neglected. Such an abstraction from age-dependent variations in molecular characterisations of cancer subtypes is a useful tool, which supports an understanding of those molecular features that are common to a cancer subtype independently of patients’ age. However, having explicitly formalised knowledge about age (across domains of biomedicine and epidemiology), the understanding of ageing and its relation to particular disease behaviour would mutually enrich dispersed segments of knowledge [Sojic].

References

[Anderson+Al:2009](1, 2) Anderson WF, Jatoi I, & Sherman ME (2009) 'Qualitative age interactions in breast cancer studies: mind the gap', Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 27(32), pp.5308-11. [PMID:19826117]
[Jatoi+Al:2008]Jatoi I, Anderson WF, & Rosenberg PS (2008) 'Qualitative age-interactions in breast cancer: a tale of two diseases?', American journal of clinical oncology, 31(5), pp.504-6. [PMID:18838890]
[Thomas+Leonard:2009]Thomas GA & Leonard RC (2009) 'How age affects the biology of breast cancer', Clinical oncology (Royal College of Radiologists (Great Britain)), 21(2), pp.81-5. [PMID:19071000]


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