The study of factors affecting cancer is known as cancer epidemiology. It helps to infer possible trends and causes. The study of cancer epidemiology uses epidemiological approaches to discover the cause of cancer and to classify and develop improved treatments. Observational epidemiological studies that show relation between risk factors and specific cancers mostly aid to generate hypotheses about potential interventions that could reduce morbidity or cancer incidence. Randomized controlled trials then test whether hypotheses generated by epidemiological studies and laboratory research result in reduced cancer incidence and mortality. In many instances, results from observational epidemiological studies are not confirmed by randomized controlled trials.