Colorectal cancer (CRC) is one of the most common malignant tumors. The probability of suffering from colorectal cancer in a person’s life is 6%. There are about 1.20 million new colorectal cancer cases in the world each year. Nearly 600,000 people die of colorectal cancer each year. Among all malignant tumors, both incidence and mortality of colorectal cancer are in the third position. In recent years, incidence and mortality of colorectal cancer in western-developed countries have decreased a little, whereas incidence of colorectal cancer in developing countries has still showed a rising trend.