Abstract
The risk of cancer in inflammatory bowel disease (IBD) is increased although it remains low. A clinical subgroup of patients with extensive or total ulcerative colitis and a history of symptoms for more than 10 yr is at greatest risk. In these patients biopsy evidence of epithelial dysplasia has successfully been used as a marker for increased cancer risk. A classification system for dysplasia has recently been devised, consisting of 3 categories: negative, indefinite and positive for dysplasia. The criteria for each category are discussed. For patients at high risk who decline prophylactic colectomy, a cancer surveillance programme involving periodic clinical assessment, sigmoidoscopy, colonoscopy and rectal and colonic biopsies has provided a reasonable alternative.