Epidemiology is the study of who gets cancer and why.
Epidemiologists specializing in cancer examine the relationship between a number of risk factors for cancer, such as which types of cancer occurred, and which people were affected. Researchers then use this information to develop strategies to help people reduce their risk of cancer. Studies of specific segments of the population over a period of time help researchers understand the causes of cancer. This includes helping to identify specific characteristics that may have contributed to a certain group of people developing cancer. These types of studies are called population-based studies because they are based on examinations of a particular segment of the population.