尽管外科及放射治疗有所改进,但大肠癌的死亡率在过去的50年内仍维持原状。辅助化疗在存活率方面亦未取得满意的疗效,以致约有58％的病人从诊断后5年内死亡,为美国和西方国家第二位肿瘤死亡原因的癌。虽然癌何时发生尚不清楚,但许多作者同意这样的看法,即在癌表现出来时,可能已经历了几十年了。在此期间多种促进因素影晌着大肠粘膜,使其最终导致一个或几个细胞恶变并发展为癌。 Despite improvements in surgery and radiation therapy, the mortality rate of colorectal cancer has remained unchanged in the past 50 years. Adjuvant chemotherapy has also failed to achieve a satisfactory therapeutic effect in terms of survival rate. As a result, approximately 58% of patients died within 5 years after diagnosis. This is the second leading cause of cancer death in the United States and Western countries. Although it is unclear when cancer occurs, many authors agree with the view that cancer may have been going through for decades. During this period, a variety of promoting factors affect the mucosa of the large intestine, which eventually leads to the malignant transformation of one or several cells and the development of cancer.