Dysplasia in inflammatory bowel disease: Clinical pathology and current surveillance methods

Abstract

Inflammatory bowel disease (IBD) predisposes to the development of colorectal carcinomas. In ulcerative colitis (UC) the highest risk occurs in those patients with extensive colitis for more than 10 years. This risk is accentuated if the disease began at an early age [1-3], and appears to be less if the inflammation is confined to the left side of the colon [4]. Crohn's colitis, while initially thought to have a low risk [4] is now recognized to have a risk comparable to that of UC [4-6]. The management of the cancer risk in those patients with IBD can be problematic. Patients with severe symptoms are more likely to have a colectomy as a result of these symptoms, while those with minimal or no symptoms are actually at the highest risk as their colons are spared. As it is difficult to apply relative risks to the individual patient, the patient's age and general health are considerations when considering the relative morbidity and mortality of possible options. Fortunately, the advent of ileal pouch-anal anastomosis techniques has made prophylactic colectomy more attractive, particularly to the young, as an alternative to continent or noncontinent ileostomies. Periodic surveillance by colonoscopy with adequate biopsies of the epithelium to assess for dysplasia has also become utilized to aid in controlling the risk of carcinoma. The rationale for this method of surveillance derives from the hypothesis that cancer in UC evolves through a premalignant phase of dysplasia which can be detected on biopsy [7], and which identifies the patient who requires a colectomy for cancer prevention even if the colon is clinically asymptomatic. The results of long-term studies suggest that surveillance by biopsy may have an effect on reducing cancer risk and mortality [8-11], though since most patients with UC will not develop cancer, the cost-effectiveness is moderate [12]. This chapter will examine the morphologic criteria for dysplasia in idiopathic IBD, the biologic characteristics and significance of dysplasia, and summarize current management and surveillance strategies. © 2005 Springer Science+Business Media, Inc.