Dysplastic lesions in ulcerative colitis: changing paradigms.

Crohn and Rosenberg first highlighted the increased risk of colorectal cancer in ulcerative colitis in 1925. Cancer rates as high as 34 percent after 30 yrs of disease have been reported in several population-based studies, although the reported risk varies substantially. Lower rates have been reported in: population-versus specialist centre-cohorts, local practices with a high colectomy rate and high 5-aminosalicylate usage, and more recent as opposed to older reports. Despite this variation in reported risk, and lack of controlled evidence for cancer reduction, colonoscopic surveillance programmes are a routine part of care in many centres. Cancer is believed to arise most commonly in dysplastic epithelium, and the detection of either dysplasia or early cancer forms the basis of such programmes. Further confusion stems from the variety of terms used to describe dysplastic change.