0　引言在中国 ,随着人们生活方式的改变 ,大肠癌的发病率逐年上升。 1992年统计结果肠癌的死亡率已位于恶性肿瘤死亡率的第 5位。由于大肠癌的病因及发病机制仍未完全明了 ,所以大肠癌的治疗一直不能令人满意。在未明确病因及癌变机制之前 ,通过病因预防来降低大肠癌的发病率 0 Introduction In China, as people’s lifestyle changes, the incidence of colorectal cancer increased year by year. The 1992 statistical results of colorectal cancer mortality rate has been located in the fifth cancer death rate. Because of the etiology and pathogenesis of colorectal cancer is not yet fully understood, so the treatment of colorectal cancer has been unsatisfactory. In the absence of a clear cause and mechanism of cancer, through the prevention of etiology to reduce the incidence of colorectal cancer