Cancer epidemiology: substance and methods

RESUMO

Cancer epidemiology is the scientific discipline that studies the occurrence of neoplastic diseases in man, their risk factors and how they are distributed in populations. Cancer epidemiology also encompasses the study of clinical outcomes in human cancer, such as disease recurrence, second tumors, and death, as well as of their determinants, the so-called prognostic factors. Well accepted discoveries from epidemiologic investigations coupled to experimental evidence from other disciplines form the mainstay of cancer prevention, e.g., the role of tobacco smoking, diet, and environmental exposures, and that of screening. For a long time, epidemiologists have held the belief that tumors do not contain traces of the carcinogens that caused them. This belief, product of the inadequate laboratory tools of the past, has reflected on the "black box" nature of much of the epidemiologic research on cancer. Recent progress in allied scientiric fields such as, molecular and cell biology, and immunology, has provided a promising set of tools for the study of cancer causes and prognostic factors. Use of these tools in epidemiology has afforded for the first time the opportunity to probe more intimately the mechanisms of carcinogenesis and clinical progression.