Colorectal Cancer Screening UK

Nigel Williams

Powerpoint File

Consultant Surgeon, University Hospitals Coventry and Warwickshire

The pathogenesis of colorectal cancer (CRC) lends itself to population screening. The various methods of screening for CRC all have cost-effectiveness ratio comparable to those of other generally accepted screening tests (1)

Faecal occult blood testing (FOBT) as a means of screening for CRC is based on the observation that cancers are more likely to bleed than normal mucosa. About 70% of cancers bleed in the course of a week (2). The most widely used tests are based on a guaiac-based test for peroxidase activity. The sensitivity of the test is increased with the number of stool samples tested. The first randomised trial of FOBT for CRC screening was performed in Minnesota (3) and this demonstrated a reduction in CRC-specific mortality in the screened group. The Nottingham study demonstrated an 15% reduction in CRC mortality in the screened group, after a mean follow-up of 7.8 years after the study had begun (4). Based on these and many other studies, the UK Colorectal Cancer Screening Pilot was established to determine the feasibility of screening for CRC in the UK population using FOBT. The English site was based in Warwickshire and in Scotland, the population of Dundee were selected.

In the UK arm, 174 725 people 50-69 were predicted for inclusion but in fact 187 777 were identified. The target group was identified through General Practitioner patient lists and the population was screened sequentially by geographical location. FOBT kits were posted to all individuals in the predetermined age group. There was an uptake of approximately 60%. The general uptake was lower in men, younger people, those from deprived areas and individuals of ethnic minorities. The uptake was slightly higher in the UK population. The overall positivity rate was 1.5% of kits returned (which is slightly lower than the Nottingham results) and 82% of these went on to a colonoscopy within the pilot. A small proportion declined, were excluded for medical resaons or had their colonoscopy performed privately. Of those patients undergoing colonoscopy, approximately 60% were normal, 30% had polyps and 10% had a cancer. Generally, Dukes A and B were overrepresented compared to a symptomatic population. It is too early for mortality and long-term survival data to be available.

The UK Pilot had a modest but discernible impact on workload in primary care. There was a considerable impact on workload in secondary care. There is general consensus that capacity to provide additional colonoscopy services will be critical in the roll-out of a national program. There has been a substantial (up to 30%) increase in the workload a GI pathologist. Indeed, in England, a total of 1789 ‘polyps and other biopsies’ were generated over the course of the Pilot (plus an additional 120 resection specimens).

The Pilot has highlighted the likely impact of such a national screening program on the workload in primary and secondary care. Information technology proved a major hurdle in the initial set-up and had identified other hurdles to be cleared. The likely success of a national program can only be assured if funding is adequate and the essential diagnostic services are in place to deal with individuals found to have pathology. The Department of Health has however funded the program for a further 2 years commencing 2002 and this may yet generate sufficient data to prompt the roll-out of a national program

References

1. Wagner JL, Tunis S, Brown M, Ching A, Almda R. Cost-effectiveness of colorectal cancer screening in average-risk adults. In G Young and B Levin, eds., Prevention and early detection of colorectal cancer. London: Saunders, 1996

2. Young GP, St John JB. Selecting an occult blood test for use as a screening tool for large bowel cancer. Front Gastrointest Res 1991; 18:135-56

3. Mandel JS, Bond JH, Church TR et al. Reducing mortality from colorectal cancer by screening for faecal occult blood. Minnesota Colon Cancer Control Study. N Engl J Med 1993;328: 1365-1371

4. Hardcastle JD, Chamberlain JO, Robinson MHE et al. Randomised control trial of faecal occult blood screening for colorectal cancer. Lancet1996 Nov 30;