Epidemiology

It often focuses on the frequency, pattern, causes and risk factors of these events, which can include environmental exposures, infectious and non-infectious diseases, natural disasters and terrorism. The populations in question can range from small, localized groups, such as a single neighborhood, to the entire global population. Epidemiological studies usually come in four forms: cluster studies, which analyze instances of unusually high cases, either regarding location or time period; ecological studies, which focus on larger, more generalized populations; case-control studies, which focus on the frequency within a population; and cohort studies which directly compare an exposed group to an unexposed group.

The results of an epidemiological study are used to plan and evaluate strategies for the prevention and management of detrimental health events, in addition to the care of patients already suffering due to such events. Epidemiologists are often employed by government agencies, in order to improve the health of the population as well as to consider the economic impacts of health care responses. Therefore, epidemiology requires an understanding of multiple fields beyond that of health, such as politics, economy and sociology.

Within oncology, epidemiology plays an important role in identifying potential causes and risk factors for multiple cancers. Studies have identified several lifestyle factors that can increase the risk for developing cancer, such as smoking and obesity, as well as factors that can decrease the risk, such as longer leisure time.
Epidemiological studies can also focus on the treatment of cancer, specifically patient inequalities and diagnostic opportunities. Often studies such as these focus on prevalence across multiple populations. Cancer epidemiology is a fast-growing field of research with many institutions creating specific units for this area, such as University College London (UK/ ECHO), Oxford University (UK/ CEU) and The Institute of Cancer Research (London, UK/ CEPRU).