The difference between proctitis and rectal cancer lies in the different causes, clinical manifestations and treatments of these two diseases. 1. Different causes: proctitis can be related to inflammatory bowel disease, radiation therapy, infection, use of antibiotics, bad dietary habits and so on; while rectal cancer is mainly related to environment, polyps, diet and heredity and other factors. 2. Different clinical manifestations: patients with proctitis may have acute and severe bowel problems, accompanied by pain in defecation, blood in stool, diarrhea, constipation and other defecation abnormalities; rectal cancer may have no obvious symptoms in the early stage, but when the cancer affects defecation or breaks down and bleeds, the patients may have symptoms similar to those of proctitis, but the patients with rectal cancer may have the symptoms of emaciation, fatigue, intestinal obstruction and so on. 3. Different treatment methods: the main treatment method of proctitis is medication, and for patients who are difficult to be controlled by conservative treatment, surgery is needed. Proctitis generally has a good prognosis through active and effective treatment. While the main cure for rectal cancer is surgery, radiotherapy and chemotherapy (e.g. 5-FU, furanuridine, etc.) are also needed as adjuvant treatment before and after surgery to improve the chance of cure. The treatment of rectal cancer focuses on prolonging patients’ life and improving the quality of survival. If patients have any discomfort, they should go to the hospital in time to find out the cause of the disease and actively cooperate with the doctor’s treatment.