Incidence and distribution of advanced colorectal adenomas in patients undergoing colonoscopy for screening, surveillance, and symptoms

PURPOSE: The aim of the study was to determine the frequency and distribution of advanced colorectal adenomas (ACAs) in Chinese population. METHODS: The patients who were referred to receive a colonoscopy were divided into three subgroups of screening, surveillance, and symptomatic, and then they were selected based on their indications. The symptomatic subgroup was further broken down into the alarm and non-alarm categories. The location and morphology of all colorectal lesions were both investigated and recorded. RESULTS: There were significantly more patients with ACAs in the symptomatic subgroup compared to the screening or surveillance subgroup (11.0% vs 4.1%, P<0.001; 11.0% vs 4.6%, P=0.006). No differences were found in the ACA frequency between the alarm and non-alarm categories (11.7% vs 9.7%, P=0.056). One observation was that in the symptomatic subgroup, distal lesions were more likely to contain ACAs than proximal ones (OR 1.50, 95% CI 1.05–2.15, P=0.024). It was also noted that nonpolypoid lesions had significantly higher amounts of ACAs in the symptomatic subgroup (OR 2.09, 95% CI 1.48–2.94, P<0.001) than the other groups. CONCLUSION: The incidence of ACAs was higher in patients undergoing a colonoscopy due to their symptoms, compared to the incidence in those who underwent the procedure for screening or surveillance purposes. Additionally, more attention should be focused on distal and nonpolypoid lesions to improve the detection rate of ACAs.