Causes of death currently still rank first in China in terms of tumors. The incidence rates are ranked as follows: lung cancer, liver cancer, stomach cancer, rectal cancer, esophageal cancer, etc. The incidence rate of rectal cancer in the world is increasing at the rate of 2% per year, while the survey in Shanghai shows that the incidence rate of rectal cancer in China is twice as fast as the world level, reaching 4%. So why is the incidence of rectal cancer in China so high? 1.Change of diet and living habits Due to the change of living habits in recent years, overeating and irregular diet have provided the prerequisite for the rise of rectal cancer. According to incomplete statistics, 80% of the incidence of rectal cancer is the result of pre-cancerous lesions, in order to avoid the occurrence of rectal cancer, the recognition and treatment of pre-cancerous lesions is extremely important, the main pre-cancerous lesions of rectal cancer are as follows: colon polyps: colon cancer mostly comes from polyps “transformation” Colon polyps are superfluous organisms that bulge on the surface of the colon mask and protrude into the lumen, and they occur mostly in the sigmoid colon and rectum, more in men than in women, and the older the age, the higher the incidence. papillary adenomas, which have a tendency to become cancerous. It is generally believed that the cancer rate of polyps increases with the size of the polyps, the majority of polyps less than 0.5cm are benign, the cancer rate is only 0.6%, above 1.0cm, about 6%, above 2.0cm the cancer rate can reach 20%, above 4.0cm is mostly malignant, so polyps in the intestine once found should be promptly removed under the microscope. Inflammatory bowel disease: mainly includes chronic colitis, chronic non-specific ulcerative colitis, Crohn’s disease, etc. Inflammatory bowel disease cannot be cured in time, and the intestinal mucosa is stimulated by inflammation for a long time, which can cause the formation of intestinal mucosal polyps, especially the interaction between bacteria and bile acids, which increases the cancer rate. Hemorrhoids, anal fistula, anal papilloma, anal polyps and other anal diseases: Although hemorrhoids cannot be directly cancerous, many patients and doctors misdiagnose or fail to detect tumors in time because of hemorrhoids account for about 50% or more of rectal cancer patients. The cancer rate of anal fistula with repeated episodes of pus flow and long-term irritation for more than ten years is also reported from time to time. Anal papilloma and anal polyps are also a factor of cancer.