Epidemiology of stomach cancer in Japan. With special reference to the strategy for the primary prevention.

Characteristics of both descriptive and analytic epidemiology of stomach cancer were summarised. Dietary changes, especially reduced intake of salted food mainly due to the wider use of electric refrigerator, were considered as the major reasons of recent decline in mortality. Other features of descriptive epidemiology such as socio-economic variation, lower risk in Okinawa residents and Japanese migrants to the U.S.A. were also described. In analytic epidemiology, daily cigarette smoking was found as a risk-enhancing factor in addition to frequent intake of salted food. Daily intake of green-yellow vegetables, soybean paste soup and milk were considered as risk reducing factors. Possibilities of primary prevention of stomach cancer was discussed based on these findings.