Ulcerative proctitis is more likely than normal to be cancerous, and the likelihood of cancer increases with the course of the disease, but overall the likelihood of cancer in ulcerative proctitis is relatively small. Ulcerative proctitis, the cause of which is unclear, is a diffuse inflammatory disease of the colorectum. In general, the probability of cancer increases with the progression of the disease. The probability of cancer in ulcerative proctitis within 8 years is very low, but the probability of cancer increases dramatically in those who have had the disease for more than 30 years. At present, there are fewer statistical studies on ulcerative proctitis in China, but foreign studies on the probability of cancer show that the incidence of cancer in patients with 10, 20 and 30 years of disease is 2%, 8% and 18% respectively, and the average time of cancer is 23.5 years. Southern Medical University has also conducted a study on the domestic population, and the cancer incidence rate of patients with 10, 20, and 30 years was 1.15%, 3.56%, and 14.36% respectively, with an overall average cancer incidence rate of 0.87%. Therefore, on the whole, the probability of ulcerative rectal cancer is very small, and as long as it receives standardized treatment at an early stage, cancer will almost never occur.