Chronic colitis and proctitis may be cancerous. Bacterial colitis and proctitis are generally less likely to become cancerous, and ulcerative colitis is a precancerous lesion of colorectal cancer; the factors that cause colorectal cancer include environmental factors, genetic factors and other high-risk factors. 1. Environmental factors: excessive intake of high-fat food such as pork, low dietary fiber, etc., leading to intestinal microecological disorders and causing the occurrence of colorectal cancer. 2. Genetic factors: familial adenomatous polyposis, hereditary non-polyposis colorectal cancer and gene mutation can lead to colorectal cancer. 3. High risk factors: colorectal adenoma and inflammatory bowel disease, especially ulcerative colitis, are the most common and important factors causing colorectal cancer, and the possibility of cancer is extremely high. Besides, those with family history of colorectal cancer, positive fecal occult blood, own history of cancer or long-term smoking, drinking and obesity have higher risk of colorectal cancer than normal people. Chronic colorectal and proctitis patients do not need to worry too much, usually take more rest and do not stay up late, quit smoking and drinking, do not eat spicy and stimulating food, eat more fresh vegetables and fruits, keep the bowel movement smooth, and develop the habit of regular defecation, which can effectively prevent the occurrence of colorectal cancer. If you have any discomfort symptoms, you should go to the hospital in time and consult your physician for guidance.