Risk factors for advanced colorectal neoplasms in the proximal colon in 6218 subjects undergoing complete colonoscopy

BACKGROUND AND AIM: Proximal migration of colonic lesion has been observed; however, risk factors of lesions in the proximal colon remain uncertain. This study aimed to investigate risk factors of lesions in the proximal colon. METHODS: Consecutive subjects with complete colonoscopy were included. The primary outcome was risk factors associated with advanced neoplasm (AN) and serrated lesion in the proximal colon. Age, gender, first-degree relative (FDR) with colorectal cancer (CRC), smoking, alcohol consumption, body mass index, hypertension, diabetes, ischemic heart disease, and the use of aspirin, non-steroidal anti-inflammatory drug, and anticoagulants were fitted into a regression model, with reference to subjects without colonic finding. Results were measured by odds ratio (OR) with 95% confidence interval (CI). RESULTS: Among 6218 subjects (mean age 56.65 ± 6.15 years; 46.8% male), 352 (5.7%) had AN; 809 (13.0%) had serrated lesions, and 3648 (58.7%) had no colonic finding. There were 148 (2.4%) and 235 (3.8%) subjects having AN and serrated lesion in the proximal colon. Age ≥ 50 (OR: 13.30; 95% CI: 1.85-95.76), male gender (OR: 1.82; 95% CI: 1.26-2.62), FDR with CRC (OR: 2.12; 95% CI: 1.43-3.15), and hypertension (OR: 1.86; 95% CI: 1.30-2.68) were associated with AN in the proximal colon. Age ≥ 50 (OR: 5.72; 95% CI: 2.10-15.53), male gender (OR: 1.54; 95% CI: 1.15-2.05), and smoking (OR: 1.85; 95% CI: 1.23-2.79) increased risk of serrated lesions in the proximal colon. CONCLUSION: Age ≥ 50 and male gender were associated with both proximally located AN and serrated lesion; FDR with CRC and hypertension increased the risk of proximal AN, while ever smoking increased the risk of proximal serrated lesion. FDR with CRC was not associated with serrated lesion.