大肠癌在欧美各国是癌肿中居第二、三位的常见肿瘤。美国1987年统计大肠癌的估计发病数及死亡数均为第二位。国内大肠癌的发病率亦在逐年上升,上海统计80年代较70年代增加48.1％。因此,也已成为主要癌肿之一而受到重视。国内大宗病例报道,早期病变的发现仍居少数,即使中晚期病变已引起明显症状而被延误诊断的为数也还不少。近年来虽有气钡双重 Colorectal cancer is the second and third most common tumor in cancer in Europe and the United States. In the United States in 1987, the estimated incidence and number of deaths of colorectal cancer were the second highest. The incidence of colorectal cancer in China is also rising year by year. Shanghai statistics increased by 48.1% in the 1980s compared with the 1970s. Therefore, it has become one of the major cancers and has received attention. A large number of cases in China have reported that the early stage lesions are still rare. Even though the middle and late stage lesions have caused obvious symptoms, the number of delayed diagnosis is still quite a few. Although in recent years there is a double