Abstract
As the number of cancer deaths has increased, the number of cancer researchers including cancer epidemiologists has increased. Compared to the approaching methods of epidemiologic studies on cardiovascular diseases, those of cancer epidemiology are different. In cancer epidemiology a case-control study has been used most frequently, while in cardiovacular disease epidemiology a cross-sectional study with health examinations in a defined population has been used most frequently. In the latter study a cross-sectional study has been repeated periodically forming a cohort study in a model area. Only few large scale cohort studies on cancer had been conducted previously, but in recent years several large scale cohort studies on cancer have been conducted by several research groups. In recent years there is a trend that epidemiologists in cancer, cardiovascular diseases and other related areas collaborate in conducting a large scale cohort study. Chemoprevention studies on cancer have been initiated by cancer epidemiologists in recent years.
