Around 16,000 people die from colorectal cancer in the UK every year, with annual health-care costs for treatment of the disease estimated at 300 million. Survival rates exceed 90% if the disease is detected at an early stage; population screening is feasible as most invasive tumours develop slowly from non-cancerous polyps. In the UK, flexible sigmoidoscopy is judged a more suitable tool for population screening than colonoscopy (advocated in the USA), because it is safer, cheaper, quicker, and more convenient, and uptake rates are much higher. Two thirds of adenomas and cancers are located in the rectum and sigmoid colon, which is within reach of the flexible sigmoidoscope, and the procedure takes only five minutes.
The trial was led by Wendy Atkin and colleagues from Cancer Research UK. Men and women aged 5564 years from 14 UK centres were randomly assigned screening or control (ratio one to two). The control group was not contacted. Small polyps were removed during screening, and individuals were referred for colonoscopy if high-risk polyps were found.
Around 170,000 individuals were randomised. Attendance among those assigned screening was 71%. 2131 (5%) were classified as high-risk and referred for colonoscopy; 38 525 (95%) with no polyps or only low-risk polyps detected were discharged. There was one perforation in 40,000 flexible sigmoidoscopy examinations, compared with four perforations among 2377 patients given colonoscopy. An average of 48 people were screened, and two or three colonoscopy referrals generated, per centre each week.
In an accompanying Commentary (p 1266), David Ransohoff from the University of North Carolina, USA, concludes: The UK investigators raise provocative question
Contact: Richard Lane