Abstract
Mortality from colorectal cancer has markedly increased in Japan over the past decades. Much attention has been drawn to a hypothesis that low-fiber and high-fat diet may increase the risk of colorectal cancer. However, this hypothesis has not necessarily been supported by recent epidemiological studies. Available evidence indicates that vegetable consumption convincingly confers protection against colorectal cancer and that red meat probably increases the risk. Epidemiological findings indicate that physical activity is undoubtedly protective against colon cancer. Colorectal adenoma itself is a benign neoplasm, but is a well-known precursor lesion of colorectal carcinoma. Studies of colorectal adenoma have an advantage in that the exposure in the recent, rather than distant, past is relevant to the risk of adenoma. We have investigated lifestyle factors associated with sigmoid colon adenoma in the Self Defense Forces Study, which is based on a health examination program. Physical inactivity and central obesity were related to an evident increase in adenoma risk. Smoking was also shown to be strongly associated with increased risk of adenoma while a modest increase in adenoma risk was observed in relation to alcohol drinking. The author recommends that epidemiological studies be developed in the health examination programs in communities and working places to advance behavioral health science.
