How to monitor for colon cancer in patients with ulcerative colitis The most serious complication in patients with ulcerative colitis (hereafter referred to as UC) is colon cancer, especially in those with a long course, extensive lesions, and coexisting primary sclerosing cholangitis. This may be related to the long-term chronic inflammation of the mucosa inducing cellular heterogeneous proliferation, which eventually leads to malignant tumor formation. A family history of colon cancer may further increase the risk of malignancy in these patients. So, what can be done to prevent the occurrence of colon cancer? It has been suggested that prophylactic total colectomy can reduce the risk of colon cancer, but it is not suitable or acceptable for all patients. However, once a definite heterogeneous hyperplasia is detected, the patient is at a significantly increased risk of developing colon cancer in the near future and prophylactic total colectomy should be considered. Studies suggest that 5-aminosalicylates may reduce the risk of colon cancer and therefore may be used as long-term preventive therapy in most patients. However, this alone is not sufficient to reduce the incidence of malignancy. Early detection of precancerous lesions of colon cancer and timely intervention are the most effective ways to reduce the risk of colon cancer. “Surveillance colonoscopy is the most reasonable and important surveillance method for patients at risk of colon cancer. Surveillance colonoscopy is different from ordinary colonoscopy in that one piece of tissue is taken every 10 cm in each of the four quadrants, and additional biopsies are required to detect suspicious augmentation lesions for the purpose of early detection of heterogeneous growths (i.e. precancerous lesions). Timing of surveillance colonoscopy The most accepted opinion among clinicians and specialists is that patients with extensive colitis of more than 10 years’ duration should begin to undergo surveillance colonoscopy. The application of stained endoscopy or magnified endoscopy has the potential to improve detection rates. If cancer or heterogeneous hyperplasia is detected during surveillance, surgical intervention is required. If a patient has coexisting primary sclerosing cholangitis, colon surveillance should be advanced to the time of diagnosis because of their greatly increased risk of developing colon cancer. The incidence of bowel cancer in patients with simple proctitis is comparable to that of the general population and does not require special surveillance. It is important to note that because the extent of lesions in UC is a dynamic process and the site of inflammatory involvement usually changes over time, extensive colonic lesions in this context are those where inflammation is found to exceed the splenic area at any given colonoscopy, regardless of whether this is the case at the time of diagnosis. Surveillance intervals US guidelines recommend that surveillance of patients with total and left hemicolectasis begin after 10 years of disease and be repeated every 1-2 years thereafter; this is extended to 1-3 years for 2 consecutive negative findings until the disease reaches 20 years. Thereafter, surveillance should be intensified at a frequency of 1-2 years. However, the UK guidelines recommend initial screening at 10 years of disease, monitoring every 3 years for the first 10 years, every 2 years for the second 10 years, and once a year thereafter. Patients with primary biliary cirrhosis are at significantly higher risk of colon cancer and require annual surveillance colonoscopy. Recent evidence suggests that sustained maintenance of disease remission may significantly reduce the risk of colon cancer and that longer surveillance intervals may be appropriate in these patients.