Colonoscopic surveillance in ulcerative colitis--dysplasia through the looking glass.

Colonoscopic surveillance in ulcerative colitisdysplasia through the looking glass Reflection Carcinoma was first described as a complication of ulcerative colitis (UC) by Crohn and Rosenberg in 1925.' Since then many workers have attempted to quantify the degree of increased cancer risk associated with UC. Most early studies tended to overestimate the degree of risk, calculating cumulative cancer rates ranging from 16% to 43% depending on the duration of disease.2' In contrast, Hendricksen (in Denmark)' and Maratka (Czechoslovakia)6 have produced figures for cumulative risk of 1*4% and 5% at 18 and 20 years from onset respectively. The reasons for such wide discrepancies in the assessment of cancer risk have been well reviewed by Whelan7 and Lennard-Jones.i They relate to inadequate follow up, differ- ences in study populations, treatment policy and methods of analysis. More recently, in a retrospective cohort study which took these criticisms into account, Gyde et al' report cumulative risks for cancer in extensive colitis of 7.2% at 20 years and 16-5% at 30 years, while in a population based study in Israel, Gilat et al'found an incidence of 9.3% and 13.8% at 15 and 20 years respectively for total colitis.