The clinical relevance of epidemiology: an overview

Epidemiology is one of the areas of medical research which by definition should have immediate clinical implications, since its inferences are based on and apply to humans and should in theory be directly transferable to clinical and preventive measures. However, interchange of information has not always been easy, and this has constituted a substantial drawback to both the epidemiologist and the clinician. This review paper will provide some points for discussion, with special emphasis on cancer epidemiology and aspects of specific interest to the clinician, i.e., quantification and risk assessment for primary prevention and cost/benefit evaluation for secondary prevention and cancer treatment. Quantitative assessment is of major importance for the oncologist in at least three areas: cancer trends (descriptive epidemiology), cancer risks (analytical epidemiology), and preventive and therapeutic measures (clinical epidemiology).