Association between lifestyle and site-specific advanced colorectal lesions in screening with faecal immunochemical test and sigmoidoscopy

Background: Lifestyle factors may help to identify individuals at high-risk for colorectal cancer (CRC). Aims: To examine the association between lifestyle, referral for follow-up colonoscopy and proximal neoplasia detection in CRC screening. Methods: In this observational study, 14,832 individuals aged 50-74 years were invited to faecal immunochemical test (FIT) or sigmoidoscopy screening. Advanced lesions (AL), including advanced adenomas, advanced serrated lesions and CRC were divided according to location: distal-only, or proximal with or without distal AL. We collected information on smoking habit, body mass index and alcohol intake through a questionnaire. Results: Out of 3,318 FIT and 2,988 sigmoidoscopy participants, 516 (16%) and 338 (11%), respectively, were referred for follow-up colonoscopy after a positive screening test. Two-hundred-and-fifty-six (4%) had distal-only and 119 (2%) proximal AL. In FIT participants, obesity and high alcohol intake were associated with proximal AL; odds ratio (95% confidence interval) 2.68 (1.36-5.26) and 2.16 (1.08-4.30), respectively. In sigmoidoscopy participants, current smoking was associated with proximal AL; 4.58 (2.24-9.38), and current smoking and obesity were associated with referral for colonoscopy; 2.80 (2.02-3.89) and 1.42 (1.01-2.00), respectively. Conclusion: Current smoking, obesity and high alcohol intake were associated with screen-detected proximal colorectal AL. Current smoking and obesity were associated with referral for follow-up colonoscopy in sigmoidoscopy screening