Formal discussion of: epidemiology of cancer: spatial-temporal aggregation.

on the epidemiology of cancer, there are no completely unrelated or independent entities and events. In Japan an old proverb says that when the wind blows, a cooper will flourish. Japan is famous for her windy days. It was believed in olden times that when the wind blew, blind persons increased in number. The blind used to earn their living by playing a sort of string instrument that was made of the skin of a cat. Because of the in creased necessity for the instruments, cats would be sacrificed. In turn, the number of rats, which gnawed the rice containers made of wood, would increase. Thus a cooper will flourish. This old saying connotes that a number of events in this world are connected with each other by indirect or unexpected relationships. An occasion has been encountered when definitive factors which would be directly related to carcinogenesis can be clearly identified through a survey of cancer epi demiology. The achievement of Percivall Pott was a pioneer work in this field. Successively, causative factors of cancer have been investigated by many workers. Some factors concerning occupational cancers have been detected so far. Furthermore, cancer of rainbow trout as an example of cancer in animals was found after feeding with artificial foods. The majority of epidemiologic factors of human cancer, however, still remain to be established. The method of epidemiologic survey in common prac tice, whether it is retrospective or prospective, seems to have a large defect in that the factor may happen to be beyond our expectation or imagination, and because of this it is difficult for us to take it for what would cause cancer. In spite of this, every effort must be directed toward finding carcinogenic factors and thereby grasping key points which would lead to the prevention of cancer. Since anti-cancer agents that effectively act upon the dis ease are not available at present and there is no assurance that such potent materials can be produced, our efforts in this regard are particularly significant. As Shimkin stated, cancer distribution differs, depending upon geo graphic locations, and the incidence of cancer varies from time to time. This is encouraging evidence that preven tive measures against cancer may be detected. We do not have data on cancer morbidity in a large number of areas over a period of many years. I am quite impressed by the pioneer and successive surveys …