Chronological Trend of Calorie Intake and the Incidence of Epithelial Neoplasms of the Large Intestine during the Past 30 Years in Japan

Objectives: The authors tried to elucidate the effects of food intake on the incidences of colorectal cancer and adenoma. Materials and Methods: Large intestines obtained from a series of consecutive autopsies performed at the Tokyo Metropolitan Geriatric Hospital were scrutinized to detect colorectal neoplasms. Chronological trends and age-dependent incidences of adenoma and overt lethal cancer were checked, while cancer in adenoma were included in the category of adenoma. Data on food consumption were obtained from the ‘The National Nutrition Survey in Japan’ (Ministry of Health, Labor and Welfare of Japan). Results: There were 405 cancers and 12,883 adenomas in the 7,091 large intestines examined. The incidences of cancer and adenoma increased with age; overt lethal cancer was found in 5.79% and adenoma in 56.79% of the general population ≧60 years in Tokyo. Calorie intake steeply increased since 1964, the year of the Olympic Games in Tokyo, until the early 1970s. Subsequently, it has continuously declined down to the level of the late 1940s, although the ingredients have changed tremendously. Chronological trends of the incidences of colorectal cancer and adenoma showed similar patterns as calorie intake, but, the influence of calorie intake on the incidences of cancer or adenoma was manifested 18 and 24 years later, respectively. Conclusions: (1) During the last 30 years, the incidences of colorectal cancer and adenoma were 5.79 and 56.79%, respectively, in individuals aged ≧60 years in Japan. (2) The chronological trends of both lesions showed a pattern similar to that of calorie intake, but, as the trend of cancer incidence preceded the course of adenoma by 6 years, adenoma is not the sole precursor lesion of overt lethal cancer.