Efficacy of surveillance and molecular markers for detection of ulcerative colitis-associated colorectal neoplasia

摘要

The incidence of colorectal neoplasia is increased among patients with ulcerative colitis (UC), and UC-associated colorectal neoplasia represents a major cause of increased mortality in patients with UC. Since Warren and Sommers first suggested that UC-associated dysplasia was the precursor of UC-associated cancer in the colorectum, several studies have demonstrated a correlation between both UC-associated neoplasias. There is general agreement that UC-associated cancer is preceded by dysplasia, arising through a chronic inflammation-dysplasia-carcinoma sequence. In order to improve the prognosis of patients with UC-associated neoplasia, diagnosis at an early or precancer-ous state in patients with UC is crucial. Predisposition to colorectal neoplasia in UC is generally seen to depend on two risk factors; namely, longstanding disease duration and extensive colitis. Therefore, surveillance colonoscopy with multiple-step biopsy has been recommended for patients with longstanding and extensive UC. However, because UC-associated neoplasia is often difficult to detect endoscopically and difficult to discriminate from inflammatory regenerative epithelium histologically, it remains a matter of contention whether conventional surveillance colonoscopy is effective for the early detection of UC-associated neoplasia. Based on these background factors, the present review examines the efficacy of colorectal neoplasia surveillance in Western countries and Japan. Mention is also made of adjunctive techniques for endoscopically and histologicaliy diagnosing UC-associated neoplasia, and molecular markers to aid in the identification of individuals at increased risk of neoplasia among patients with longstanding and extensive UC.