Patients with
ulcerative colitis and Crohn's
colitis face an increased lifetime risk of developing
colorectal cancer. Factors associated with increased risk include long duration of
colitis, extensive colonic involvement,
primary sclerosing cholangitis, a family history of
colorectal cancer, and, according to some studies, early disease onset and more severely active
inflammation. Although prophylactic
proctocolectomy can essentially eliminate the risk of
cancer, most patients and their physicians opt instead for a lifelong program of surveillance. This entails regular medical follow-up, management with antiinflammatory and putative chemopreventive agents, and periodic colonoscopic examinations combined with extensive biopsy sampling throughout the colon. The main objective of regular colonoscopy is to detect
neoplasia at a surgically curative and preferably preinvasive stage, i.e., dysplasia. An initial screening colonoscopy should be performed 7-8 years from disease onset or immediately in patients with
primary sclerosing cholangitis. Surveillance should then continue annually or biennially so long as no dysplasia is found or suspected. Biopsy specimens are graded pathologically as negative, indefinite for dysplasia, low-grade dysplasia, high-grade dysplasia, or invasive
cancer. The diagnosis and grading of dysplasia can be very challenging and should be confirmed by an expert pathologist whenever intervention or a change in management is contemplated. If 1 or more biopsy specimens are indefinite for dysplasia, colonoscopy intervals should be reduced. A patient with low- or high-grade dysplasia found in a discrete
adenoma-like
polyp, but nowhere else, can be safely managed with polypectomy and accelerated surveillance. However, dysplasia of any grade found in an endoscopically nonresectable
polyp and high-grade dysplasia found in flat mucosa are both strong indications for
proctocolectomy. Evidence further suggests that the same may be true even of low-grade dysplasia in flat mucosa. Chromoendoscopy holds promise for facilitating the endoscopic detection of
neoplasia. The clinical application of newer molecular methods to detect
neoplasia, particularly gene microarrays and stool
DNA testing, also deserve further study.