Risk Factors Associated with Advanced Colorectal Neoplasia in Adults Younger than Age 45

Background: Colorectal cancer (CRC) is rising in young adults between ages 20 to 49 years. CRC screening is endorsed for average-risk individuals beginning at ages 45 to 49 years. Targeting screening for individuals <45 years may be warranted if risk factors for advanced neoplasia can be identified. Aim: To identify factors associated with advanced colorectal neoplasia in adults aged <45 years. Method: Individuals ages 18 to 44 years who underwent colonoscopy at Cleveland Clinic between 2011 and 2021 with ≥1 advanced neoplasm (AN) were included. Patients with inflammatory bowel disease or inherited CRC syndromes were excluded. Demographics, comorbidities, family history of CRC, and colonoscopy indication were obtained. Patients with a normal colonoscopy constituted the control group. A multivariable logistic regression model was used to investigate the relationship between clinical variables and the presence of advanced colorectal neoplasia. Results: In all, 13,006 patients were included, of which 651 (5%) patients had AN: 404 (62%) with tubular adenoma ≥10 mm, 29 (4.5%) tubular adenoma with high-grade dysplasia, 210 (32%) tubulovillous adenomas, 27 (4%) traditional serrated adenomas, 82 (13%) sessile serrated lesions ≥10 mm, 7(2%) sessile serrated lesions with dysplasia, and 29 (4.4%) patients had a CRC. Factors associated with AN were older age (means 38.5 vs. 36.6 y), history of smoking, diabetes, non-White race, higher body mass index (29.9 vs. 28.5 kg/m 2 ), and lower vitamin D (27.6 vs. 32.2 ng/dl), all P <0.001. In the reduced multivariable model, factors associated with AN included tobacco use (OR 2.026 (current vs. never, P <0.0001), age (OR increase by 1.06 per year, P <0.0001), male gender (OR 1.476, P <0.0001), family history of CRC (OR 3.91, P <0.0001), aspirin use (1.31, P =0.035), and diabetes (OR 2.106, P 0.001). Conclusion: Increasing age, male gender, exposure to tobacco, family history of CRC, diabetes, and aspirin use were independently associated with advanced neoplasia in adults younger than 45. Targeted early screening to young adults with these risk factors may be justified. Large collaborative prospective studies are needed to validate our findings.