Abstract :
Background
This randomised controlled trial is examining the hypothesis that a single flexible sigmoidoscopy screening offered at around age 60 years can lower the incidence and mortality of colorectal cancer. We report here on acceptability, safety, feasibility, and yield.
Methods
Men and women aged 55–64 years, in 14 UK centres, who responded to a mailed questionnaire that they would attend for flexible sigmoidoscopy screening if invited, were randomly assigned screening or control (ratio one to two). The control group was not contacted. Small polyps were removed during screening, and colonoscopy was undertaken if high-risk polyps (three or more adenomas, size 1 cm or greater, villous, severely dysplastic, or malignant) were found.
Findings
Of 354 262 people asked about their interest in having flexible sigmoidoscopy screening, 194 726 (55%) responded positively, and 170 432 eligible individuals were randomised. Attendance among those assigned screening was 71% (40 674 of 57 254). 2131 (5%) were classified as highrisk and referred for colonoscopy; 38 525 with no polyps or only low-risk polyps detected were discharged. Distal adenomas were detected in 4931 (12•1%) and distal cancer in 131 (0•3%). Proximal adenomas were detected in 386 (18•8% of those undergoing colonoscopy) and proximal cancer in nine cases (0•4%). 62% of cancers were Dukesʹ stage A or locally excised. There was one perforation after flexible sigmoidoscopy and four after colonoscopy. An average of 48 people were screened, and two or three colonoscopy referrals generated, per centre each week.
Interpretation
Our flexible sigmoidoscopy screening regimen is acceptable, feasible, and safe. The prevalence of neoplasia is high, and colonoscopy referral rates of 5% are acceptable.
