Twenty years' colonoscopic surveillance of patients with ulcerative colitis. Detection of dysplastic and malignant transformation.

Endoscopic cancer surveillance in patients with ulcerative colitis has been performed for almost 3 decades. There is still no consensus on its clinical value. This study evaluates a 20-year prospective study of 143 patients with extensive ulcerative colitis and a disease duration exceeding 10 years. Colonoscopy with double biopsy specimens from nine locations of the colon was performed every 2nd year. Biopsy specimens showing dysplasia were reviewed at the end of the study. Through the surveillance dysplasia/cancer was detected in 55 patients; 7 of these patients had carcinomas, and 2 were in a possibly curable stage (Dukes A). The predictive value of low-grade dysplasia for either high-grade dysplasia or cancer was 41%. Although impaired by limiting factors, colonoscopic surveillance of chronic extensive colitis may identify patients with dysplasia and thereby prevent malignant transformation.