Patients with long-term inflammatory bowel disease (IBD), ulcerative colitis (UC) and Crohn's colonic disease (CD) have an increased risk of colorectal carcinoma (CRC). Eaden's meta-analysis has shown that the risk for CRC in UC patients is 2% at 10 years, 8% at 20 years and 18% at 30 years of disease duration. It is now accepted that the risk of colorectal cancer is equivalent in both (UC and CD) conditions. Duration of disease is recognized to be the most important risk factor for CRC development. Extent of disease in another major risk factor. Most cancers arise in patients with extensive disease, which is generally defined as extension of inflammation beyond the hepatic flexure. It was demonstrated that proctitis and proctosigmoiditis posed no increased risk for patients with UC. Recent data from case control studies suggests that greater degrees of colonoscopic or histologically active inflammation are associated with an increased risk of CRC. Recently, it has been proven that shortened tubular colon, colonic stricture and postinflammatory polyps should be considered strong risk factors for CRC development. Primary sclerosing cholangitis (PSC) in patients with UC is associated with substantial risk of CRC. Screening colonoscopy should be performed in patients with UC after 8-10 years of disease. The interval between surveillance examinations is dependent on each individual's personal risk factors. In patients with a previous history of PSC, ongoing active inflammation, previous history of dysplasia or strictures, and strong family history of bowel cancer, annual surveillance is recommended. Colectomy is strictly recommended for patients who were diagnosed with flat high-grade dysplasia (HGD) or CRC and where the diagnosis was confirmed by expert gastrointestinal pathologists. In patients with a biopsy specimen considered indefinite for dysplasia, guidelines suggest colonoscopy between 3 and 12 months. Multifocal low-grade dysplasia (LGD) is a stronger indication for colectomy. The optimal colonoscopic surveillance interval for patients who were diagnosed with a flat LGD is still unknown, but 3-6 months is often recommended. Chemopreventive agents should be used to minimize the risk of developing dysplasia or CRC in IBD patients. It has been shown that mesalazine has a preventive effect for CRC and dysplasia.
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