Screening by Chromo Endoscopy for Colorectal Cancer and Dysplasia in Ulcerative Colitis: An Algerian Prospective Cohort

Patients with longstanding extensive ulcerative colitis have an increased risk of colorectal cancer. Aims : To determine the incidence of dysplasia and colorectal cancer, in patients with longstanding ulcerative colitis. To evaluate prospectively, the proportion of dysplastic lesions detected by chromoendoscopy from targeted biopsies of macroscopically visible abnormalities, as opposed to random biopsies of colonic mucosa. Patients and methods : In this prospective study, consecutive patients with clinically inactive, longstanding UC (more than 8 years) were recruited from 4 centers; colonoscopy with chromoendoscopy using 0.1% methylene blue was performed for each patient. Four mucosal biopsy specimens were taken every 10 cm between the cecum and the rectum, with additional biopsies or removal of any mucosal abnormality. All the endoscopies were performed by a single specialist in gastroenterology. All the biopsies have been reviewed by a pathologist experienced in gastroenterology. Results: Two hundred and twenty four chromoendoscopies were performed in 106 patients. We diagnosed 49 neoplastic lesions in 31 patients; there were six adenocarcinomas, eight high grade dysplasia, 24 low grade dysplasia, and 11 lesions indefinite for dysplasia. We took 8035 random biopsies and found seven dysplastic lesions in six patients: one high grade dysplasia, two low grade dysplasia and four lesions indefinite for dysplasia. Random biopsies alone diagnosed dysplasia in two patients (1.8%), and had clinical impact only in one patient (0.9%). Conclusion : In our cohort, we experienced a high diagnostic yield of chromoendoscopy in the detection of neoplasia in high risk IBD patients. Random biopsies don’t have clinical impact and should be abandoned.