直结肠癌是一种常见的恶性肿瘤,在许多发达国家中,居恶性疾患死亡原因的第二位。1987年美国有6万人死于此病。正因为此病发病率高,如果某种诊疗措施能导致生存率的提高,那么其在临床上极有实用价值。在直结肠癌的自然病程中,症状出现相对较晚,通常在肿瘤穿过肠壁侵及邻近组织,或 Colorectal cancer is a common malignancy. It ranks second in the death causes of malignant diseases in many developed countries. In 1987, 60,000 people in the United States died of the disease. Because of the high incidence of this disease, if a certain diagnosis and treatment measures can lead to an increase in survival rate, then it is extremely useful in clinical practice. In the natural course of colorectal cancer, symptoms appear relatively late, usually through the invading intestinal wall and adjacent tissues, or