An ecological study on diet/nutrition and cancer in Japan.

Correlation or ecological studies may be useful in identifying cancer risk factors which are distributed relatively homogeneously within a population, but differ greatly between populations or between different periods within a given population. In Japan, the westernization of dietary habits has progressed remarkably in the last few decades and may have resulted in changes of incidence/mortality rates of diet-related diseases, especially cancer. Based on data from the National Nutritional Survey of Japan (1955-1993) and the vital statistics of Japan (1955-1993), we conducted correlation analyses between food/nutrient intake and cancer mortality. The present study on chronological correlations suggests the relationship between westernized dietary habits and mortality by cancers of the colon, breast, ovary and prostate and also the relationship between traditional Japanese dietary habits and mortality by stomach cancer. Our results suggest the importance of diet in the etiology of diet-related cancer. Further observation and analyses are needed to confirm the relationship between food/nutrient intake and cancer mortality, while also considering the consumption of tobacco and alcohol and improvement in cancer diagnostic and therapeutic techniques.