31 August 2023

Check Up #17 - What distinguishes cancer epidemiology and aetiology and why is each important?

According to the Merriam-Webster Dictionary, epidemiology is “a branch of medical science that deals with the incidence, distribution, and control of disease in a population”, whereas aetiology is “a branch of medical science concerned with the causes and origins of diseases”.

Check-up #17 - What distinguishes cancer epidemiology and aetiology and why is each important?

But this doesn’t mean these two areas are totally distinct. In fact, epidemiology also deals with the causes of disease. But while epidemiology involves the study of determinants and distribution of disease, aetiology attempts to confirm the causes.

Nonetheless, one important difference between them is that, while epidemiology consists in the statistical search for risk factors that can cause a given disease in a certain population at a certain time, aetiology attempts to identify the underlying causes through basic research. Moreover, it specific of each patient, since causes and effects can vary across individuals.

Once the potential risk factors have been identified by epidemiological studies, aetiological research aims to prove causality – that is, to identify the biological mechanisms that explain the link between those risk factors and the disease in case.
Everything you have just read obviously applies to Oncology – in the search for the risk factors and demographics of different cancers for epidemiology; and of their causes, for aetiology. 

As for other diseases, incidence (new cases per year of a given cancer), prevalence (all cases at a given time), and mortality are the most commonly used measures, in epidemiology, to try to identify the causes of cancer, which can be environmental and/or genetic.

The epidemiology of cancer is an essential step towards the prevention and early detection of cancer. In the book Perioperative Care of the Cancer Patient (Elsevier, 2022), the authors write: “The study of cancer from an epidemiological perspective has uncovered numerous causes of cancer. Perhaps the most well-known accomplishment of cancer epidemiology was the identification of tobacco as a cause of lung cancer in 1964. This finding revolutionised our understanding of cancer, as it was the first time that a common, modifiable behavior – tobacco smoking – was shown to result in cancer.”

As for aetiology, it uses different approaches to identify potential causes of cancer, such as cell and animal studies. Aetiologies can be intrinsic (genetic causes), extrinsic (environmental causes), and idiopathic (of unknown origin).

Research in basic cancer biology can reveal the mechanisms by which biological, chemical, and physical carcinogens initiate and promote cancer. Genetic analyses allow researchers to identify genetic changes that may be associated with cancer risk. 


Book: Perioperative Care of the Cancer Patient, (Elsevier, 2022)

By Ana Gerschenfeld, Health & Science Writer of the Champalimaud Foundation.

Reviewed by: Professor António Parreira, Clinical Director of the Champalimaud Clinical Center.
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