Cancer epidemiology is the branch of Epidemiology concerned with the disease cancer. It is the study of factors responsible for various types of cancer. Cancer epidemiology is concerned with the study of the distribution of the disease cancer in populations. Epidemiological methods are used to find the cause of cancer and to identify and develop improved treatments. Its ultimate goal is to identify risk factors that may lead to early introduction of effective preventive measures. Epidemiology is concerned with events that occur in population i.e., groups of people. Epidemiological studies are concerned not only with people who get a disease, but also with those who do not.cancer epidemiological studies may focus on precursors of cancer. Epidemiologists main concern is not only with disability illness, and death, but also with health and preventing the disease.