Should we perform sigmoidoscopy for colorectal cancer screening in people under 45 years?

BACKGROUND The strategy for preventing colorectal cancer is screening by colonoscopy, which offers a direct way for detection and removal of adenomatous polyps (APs). American College of Gastroenterology guidelines recommend that people aged >= 45 years should undergo colonoscopy; however, how to deal with people aged <= 45 years is still unknown. AIM To compare the prevalence of APs and high-grade neoplasia between the left and right colon in patients <= 45 years. METHODS A retrospective observational study was conducted at a single tertiary III hospital in China. This study included patients aged 18-45 years with undergoing initial colonoscopy dissection and pathological diagnosis AP or high-grade neoplasia between February 2014 and January 2021. The number of APs in the entire colon while screening and post-polypectomy surveillance in following 1-3 years were evaluated. RESULTS A total of 3053 cases were included. The prevalence of APs in the left and right colon was 55.0% and 41.6%, respectively (OR 1.7, 95%CI 1.6-2.4; P < 0.05). For APs with high-grade neoplasia, the prevalence was 2.7% and 0.9%, respectively (OR 3.0, 95%CI 2.0-4.6; P < 0.05). Therefore, the prevalence of APs and high-grade neoplasia in the left colon was significantly higher than in the right colon in patients aged <= 45 years. There were 327 patients who voluntarily participated in post-polypectomy surveillance in following 1-3 years, and APs were found in 216 cases (66.1%); 170 cases had 1-3 polyps (52.0%) and 46 cases had > 3 polyps (14.1%; OR 0.3, 95%CI 0.1-0.6; P < 0.05). CONCLUSION This study suggests that flexible sigmoidoscopy would be an optimal approach for initial screening in people aged <= 45 years and would be a more cost-effective and safe strategy.